On Tue, 2022-01-18 at 20:58 -0500, Lyude Paul wrote:
> Hey - so, the original issue here was that payloads were not always deleted
> when we expected them to be - correct?
>
> If I'm remembering that correctly, then (and I'm not 100% sure on this yet)
> I
> might already have noticed something very possibly wonky in how we handle
> payload allocations currently, that I found while working on the non-atomic
> removal branch that I linked to you in my previous response. Basically, in
> the
> step1() function it looks like that we follow this general flow with
> updating
> payloads:
>
> * Loop through proposed payloads and compare to previously programmed
> payloads
> - If a payload has a different allocation then it previously did, update
> the
> payload
> - If the payload is new, create it
> - If a payload no longer has an allocation, remove the payload
>
> At first glance this seems totally correct - but I'm not actually entirely
> convinced it is? Particularly because it seems like the order in which we do
> creation/deletion of payloads is totally arbitrary. To explain what I mean
> by
> that, consider a state transition like this:
>
> vcpi_slots=15 vcpi_slots=35 vcpi_slots=14
> > 1 | 2 |xxxxxxxx|
Ugh, sorry - email client messed this up. This was supposed to look like this:
vcpi_slots=15 vcpi_slots=35 vcpi_slots=14
F| 1 | 2 |xxxxxxxxx|
>
> Let's say we want to increase payload #1 from 15 to 50, and disable payload
> #2
> in the same atomic commit on DRM's side. If the order we update payloads is
> entirely arbitrary, we could end up doing this:
>
> * Increase VCPI slots payload #1 from 15->50 (total VCPI slots=99,
> overflow!)
> * Decrease VCPI slots payload #2 from 35->0 (total VCPI slots=50)
>
> Notice on the first step, we've technically overflowed the available number
> of
> VCPI slots in the payload table. This is still before step 2 though, and I
> could be totally wrong here - perhaps this is entirely OK in the real world,
> and we're allowed to overflow VC slots as long as we repair the issue before
> step 2. But so far I can't seem to find anything in the DP 2.0 spec that
> explicitly states this would be OK - which makes me think we might fail some
> payload allocations if we don't always ensure we avoid overflows in between
> VC
> payload table changes. Note that avoiding overflows would be as simple as
> just
> making sure we send all VC payload table changes that free VC slots before
> sending any that take new slots.
>
> Again - I haven't actually confirmed this yet and am hoping to test stuff
> like
> this very soon as I'm pretty close finishing up the initial attempt at
> removing the non-atomic MST code in the DRM helpers now. If my theory ends
> up
> being correct here, I can fix this in my rewrite of the MST payload
> management
> code. But I figured it might be worth mentioning in the mean time in case
> you
> think it might be relevant to the problem here :).
>
> On Wed, 2022-01-12 at 16:47 -0500, Lyude Paul wrote:
> > (CC'ing this to dri-devel, since this is basically patch review)
> >
> > Alright - so first off sorry about the broken debugging patch! I thought I
> > had
> > tested that but I guess I hadn't tested it well enough, I'll get it fixed
> > asap, but feel free to try getting to it before I do.
> >
> > As for this patch… (comments below)
> >
> > On Mon, 2021-12-20 at 02:17 +0000, Lin, Wayne wrote:
> > > [AMD Official Use Only]
> > >
> > > Hi Lyude,
> > >
> > > No rush and thanks for your time! : )
> > > Just want to help clarify what I mean that "registering a callback
> > > function"
> > > for CSN of disconnecting
> > > stream sink device (not mst branch case). Attach below the tentative
> > > patch
> > > that I planned to do. Thanks so much!
> > >
> > > Regards,
> > > Wayne
> > > ---
> > > .../display/amdgpu_dm/amdgpu_dm_mst_types.c | 53 +++++++++++++++++++
> > > drivers/gpu/drm/drm_dp_mst_topology.c | 16 +++++-
> > > include/drm/drm_dp_mst_helper.h | 1 +
> > > 3 files changed, 68 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
> > > b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
> > > index cc34a35d0bcb..d7343c64908c 100644
> > > --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
> > > +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
> > > @@ -472,8 +472,61 @@ dm_dp_add_mst_connector(struct
> > > drm_dp_mst_topology_mgr
> > > *mgr,
> > > return connector;
> > > }
> > >
> > > +void dm_dp_notify_csn_disconnection(struct drm_connector *connector)
> > > +{
> > > + struct amdgpu_dm_connector *aconnector =
> > > + to_amdgpu_dm_connector(connector);
> > > + struct dc_sink *dc_sink = aconnector->dc_sink;
> > > + struct dc_link *dc_link = aconnector->dc_link;
> > > + struct amdgpu_device *adev = drm_to_adev(ddev);
> > > +
> > > + ASSERT(dc_link);
> > > +
> > > + if (dc_sink) {
> > > + mutex_lock(&adev->dm.dc_lock);
> > > +
> > > + /*clear the remote sink of the link*/
> > > + dc_link_remove_remote_sink(dc_link, dc_sink);
> > > + dc_sink_release(dc_sink);
> > > + aconnector->dc_sink = NULL;
> > > +
> > > + mutex_unlock(&adev->dm.dc_lock);
> > > + }
> > > +}
> > > +
> > > static const struct drm_dp_mst_topology_cbs dm_mst_cbs = {
> > > .add_connector = dm_dp_add_mst_connector,
> > > + .notify_csn_disconnection = dm_dp_notify_csn_disconnection,
> > > };
> >
> > I still don't really think this is a good idea. This seems like it's just
> > adding another hotplugging path to the code in order to avoid sending
> > hotplugs
> > for non-endpoint devices. In addition to the drm_connector issues I
> > mentioned
> > before, we also really need to stop doing any kind of payload maintence in
> > hotplugging paths. The reality is any kind of payload maintanence we do
> > outside of normal modesetting paths is a relic from legacy modesetting
> > that
> > I'm dropping ASAP (more on this below), and we can't keep adding to it
> > because
> > it dramatically complicates maintanence as well.
> >
> > Sorry for repeating this point so often but - the biggest issue too is I'm
> > still not sure what it is we're even avoiding here. We know resources
> > aren't
> > released consistently, and that we're able to reproduce the behavior with
> > repeated hotplugs. We also know that if we skip sending certain hotplug
> > events, that fixes the issue. And we know we can workaround it by adding a
> > special case for forcing a payload release in DC. But none of those
> > actually
> > tell us exactly what piece of code is leaking and why, which means that
> > any
> > workarounds we're putting in to avoid this mysterious guilty section of
> > code
> > we don't entirely understand either - which means we're just adding more
> > code
> > in that no one actually fully understands. This just ends up making
> > maintence
> > difficult because every change in code nearby workarounds like this has to
> > strugle to try to figure out said workarounds in order to avoid breaking
> > things.
> >
> > I'm actually currently running into these "later" issues right now, as
> > recently I've (-actively-, finally!!!) been working on trying to remove as
> > much non-atomic MST as I can because. As it turns out - a huge amount of
> > the
> > payload maintanence code just isn't needed at all when we stop caring
> > about
> > non-atomic drivers and stick everything in atomic state structs. Step 1
> > for
> > updating updating the payload table, e.g. drm_dp_update_payload_part1(),
> > is
> > a
> > great example of how messy things have become. Here's a small sample of
> > some
> > of the stuff I've seen from just that one function so far that either just
> > don't make sense here or is totally redundant. I should note that a lot of
> > these things also come from patches I reviwed, but didn't really look at
> > as
> > closely as I should have because I was swamped at work, some are
> > historical
> > artifacts, and others are less-than-ideal patches I got wrote myself when
> > I
> > was first started working on MST and didn't know the code as well as I do
> > now:
> >
> > * We try to avoid some sort of userspace issue by using
> > drm_dp_mst_port_downstream_of_branch() to avoid releasing payloads for
> > a
> > branch if we can't prove it's downstream of the top of the topology.
> > This
> > seems to workaround either a userspace bug. This is a redundant, since
> > that's what topology refs are already supposed to be doing to the
> > extent
> > is
> > reasonably possibly. It's also unfortunately racy solution because we
> > have
> > to be able to handle the situation where a connector is removed from
> > under
> > us. That can happen at any time, including _immediately_ after we call
> > drm_dp_mst_port_downstream_of_branch() - rendering the call not really
> > useful.
> > * If we fail to validate the sink in drm_dp_update_payload_part, we don't
> > update the payload table. I think at best this solution is racy and not
> > useful, at worst it leaves us with a payload table that doesn't match
> > what
> > we attempted to set in the atomic state - which at worst brings us into
> > undefined territory where we're just plain out of sync with the reality
> > in
> > hw.
> > * Actually fun fact - mgr->payloads and mgr->proposed_vcpis both can and
> > definitely should be removed entirely. All of the info for mgr-
> > >payloads
> > could just be in the atomic state, because that + the magic of atomic
> > state
> > duplication means we'll also have an accurate view of the previous
> > state's
> > payload allocations: which renders mgr->proposed_vcpis redundant.
> >
> > Apologies for the long explanation again, but I hope that explains my
> > point
> > here a bit. I'm going to be trying to get to moving amdgpu's DSC code out
> > of
> > amdgpu and into DRM helpers as well soon, so I'm really determined to
> > clean
> > stuff up beforehand as every time I've done so it's become substantially
> > easier to make changes to this code. Things used to be even worse before I
> > started cleaning things up 2 or 3 years ago, where simple changes would
> > end
> > up
> > getting me stuck spending hours trying to dig through lockdep or memory
> > manegement issues. As well, I would be entirely unsurprised if bugs like
> > this
> > very payload leak we're working on just disappear once we've gotten rid of
> > all
> > the extraneous workarounds and state tracking here - especially with how
> > many
> > special cases we have for maintaining the payload table right now. That's
> > certainly ended up being the case in the past with a number of other
> > difficult
> > to track down issues I've dealt with in MST.
> >
> > Anyhow. I've been way more productive this year then last because I had
> > over
> > a
> > month off work and am finally not super burnt out from my job, and so far
> > I've
> > been making progress on the payload state cleanup far faster then I was
> > last
> > year :). I think if you can't figure out where the leak is coming from
> > even
> > once I get the debugging patches I mentioned fixed up, it might be a good
> > idea
> > for us to try again after I've got some of this code cleaned up. I've got
> > a
> > currently WIP branch here:
> >
> > https://gitlab.freedesktop.org/lyudess/linux/-/commit/624dd68fa804e64b5b2060e4735d7317090692b5
> >
> > >
> > > void amdgpu_dm_initialize_dp_connector(struct amdgpu_display_manager
> > > *dm,
> > > diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c
> > > b/drivers/gpu/drm/drm_dp_mst_topology.c
> > > index 857c5d15e81d..a70e26c5d084 100644
> > > --- a/drivers/gpu/drm/drm_dp_mst_topology.c
> > > +++ b/drivers/gpu/drm/drm_dp_mst_topology.c
> > > @@ -2508,6 +2508,7 @@ drm_dp_mst_handle_conn_stat(struct
> > > drm_dp_mst_branch
> > > *mstb,
> > > u8 new_pdt;
> > > bool new_mcs;
> > > bool dowork = false, create_connector = false;
> > > + bool notify_unplug_event = false;
> > >
> > > port = drm_dp_get_port(mstb, conn_stat->port_number);
> > > if (!port)
> > > @@ -2520,6 +2521,9 @@ drm_dp_mst_handle_conn_stat(struct
> > > drm_dp_mst_branch
> > > *mstb,
> > > * port, so just throw the port out and make
> > > sure
> > > we
> > > * reprobe the link address of it's parent MSTB
> > > */
> > > + /* should also consider notify_unplug_event
> > > here.
> > > + * but it's not a normal case for products in
> > > the
> > > market
> > > + */
> > > drm_dp_mst_topology_unlink_port(mgr, port);
> > > mstb->link_address_sent = false;
> > > dowork = true;
> > > @@ -2541,10 +2545,14 @@ drm_dp_mst_handle_conn_stat(struct
> > > drm_dp_mst_branch
> > > *mstb,
> > > port->ddps = conn_stat->displayport_device_plug_status;
> > >
> > > if (old_ddps != port->ddps) {
> > > - if (port->ddps && !port->input)
> > > + if (port->ddps && !port->input) {
> > > drm_dp_send_enum_path_resources(mgr, mstb,
> > > port);
> > > - else
> > > + } else {
> > > port->full_pbn = 0;
> > > + if (port->connector &&
> > > + drm_dp_mst_is_end_device(port->pdt,
> > > port-
> > > > mcs))
> > > + notify_unplug_event = true;
> > > + }
> > > }
> > >
> > > new_pdt = port->input ? DP_PEER_DEVICE_NONE : conn_stat-
> > > > peer_device_type;
> > > @@ -2557,11 +2565,15 @@ drm_dp_mst_handle_conn_stat(struct
> > > drm_dp_mst_branch
> > > *mstb,
> > > dowork = false;
> > > }
> > >
> > > + if (notify_unplug_event && mgr->cbs->notify_csn_disconnection)
> > > + mgr->cbs->notify_csn_disconnection(port->connector);
> > > +
> > > if (port->connector)
> > > drm_modeset_unlock(&mgr->base.lock);
> > > else if (create_connector)
> > > drm_dp_mst_port_add_connector(mstb, port);
> > >
> > > +
> > > out:
> > > drm_dp_mst_topology_put_port(port);
> > > if (dowork)
> > > diff --git a/include/drm/drm_dp_mst_helper.h
> > > b/include/drm/drm_dp_mst_helper.h
> > > index 78044ac5b59b..ff9e47729841 100644
> > > --- a/include/drm/drm_dp_mst_helper.h
> > > +++ b/include/drm/drm_dp_mst_helper.h
> > > @@ -525,6 +525,7 @@ struct drm_dp_mst_topology_cbs {
> > > * IRQ pulse handler.
> > > */
> > > void (*poll_hpd_irq)(struct drm_dp_mst_topology_mgr *mgr);
> > > + void (*notify_csn_disconnection)(struct drm_connector
> > > *connector);
> > > };
> > >
> > > #define DP_MAX_PAYLOAD (sizeof(unsigned long) * 8)
> > > --
> > > 2.31.0
> > >
> > > > -----Original Message-----
> > > > From: Lin, Wayne
> > > > Sent: Wednesday, December 8, 2021 11:39 AM
> > > > To: 'Lyude Paul' <lyude@xxxxxxxxxx>
> > > > Subject: RE: [PATCH] WIP: drm/dp_mst: Add support for dumping topology
> > > > ref
> > > > histories from debugfs
> > > >
> > > > No worries Lyude!
> > > > Thanks for keeping helping on this. Take your time : )
> > > >
> > > > > -----Original Message-----
> > > > > From: Lyude Paul <lyude@xxxxxxxxxx>
> > > > > Sent: Wednesday, December 8, 2021 7:05 AM
> > > > > To: Lin, Wayne <Wayne.Lin@xxxxxxx>
> > > > > Subject: Re: [PATCH] WIP: drm/dp_mst: Add support for dumping
> > > > > topology
> > > > > ref histories from debugfs
> > > > >
> > > > > Sorry! I will try to get to this tomorrow, if not then sometime this
> > > > > week.
> > > > >
> > > > > On Tue, 2021-11-30 at 08:41 +0000, Lin, Wayne wrote:
> > > > > > [Public]
> > > > > >
> > > > > > Hi Lyude,
> > > > > >
> > > > > > Finally have some bandwidth to get back to this problem!
> > > > > > I roughly went through this patch and I'm just aware that we
> > > > > > already
> > > > > > have such kind of convenient tool for a while.
> > > > > > I think it's definitely useful for us to track port/mstb reference
> > > > > > count issues and I'll start to embrace this feature for cleaning
> > > > > > up
> > > > > > those issues. Thank you Lyude!
> > > > > >
> > > > > > However, I think the issue that I was trying to fix is not related
> > > > > > to what you suggested:
> > > > > > " The idea here is that if stream resources aren't being released,
> > > > > > my guess would be that we're not dropping topology references for
> > > > > > the port which means the connector never goes away."
> > > > > > The issue I was trying to fix is about releasing
> > > > > > dc_link->remote_sinks while receiving a CSN message notifying the
> > > > > > connection status of a sst connector of a port changed from
> > > > > > connected to disconnected. Not the connection status changed of a
> > > > > > mst
> > > > > > branch device.
> > > > > > e.g.
> > > > > > src - 1st_mstb - 2nd_mstb - sst_monitor => src - 1st_mstb
> > > > > > (disconnect) 2nd_mstb - sst_monitor
> > > > > >
> > > > > > In above case, after receiving CSN, we will put topology
> > > > > > references
> > > > > > of 2nd mstb and its port which is connected with the sst monitor.
> > > > > > As
> > > > > > the result of that, we can call
> > > > > > drm_dp_delayed_destroy_port() to unregister and put the drm
> > > > > > connector.
> > > > > >
> > > > > > However, in below case:
> > > > > > e.g.
> > > > > > src - 1st_mstb - sst_monitor => src - 1st_mstb (disconnect)
> > > > > > sst_monitor
> > > > > >
> > > > > > In this case, which is the case having problem, it definitely
> > > > > > won't
> > > > > > decrease the topology references count of the port which was
> > > > > > connected to the sst monitor to zero since the port is still
> > > > > > existing in the topology. Same as the malloc reference since the
> > > > > > port can't get destroyed. Hence, the port still exists and we
> > > > > > won't
> > > > > > call
> > > > > > drm_dp_delayed_destroy_port() to unregister and put the drm
> > > > > > connector.
> > > > > > I looked up the code and drm_dp_delayed_destroy_port() seems like
> > > > > > the only place to call drm_connector_put() which means we can't
> > > > > > put
> > > > > > reference count of drm connector under this case and can't release
> > > > > > dc_sink resource by destroying drm connector.
> > > > > >
> > > > > > I would also like to point out that this resource (remote_sinks)
> > > > > > is
> > > > > > specific to different stream sinks. So if we're trying to release
> > > > > > this dc_sink resource by destroying the drm connector, it
> > > > > > conflicts
> > > > > > the idea that you suggested before that we should always keep the
> > > > > > drm connector until it's no longer reachable in the topology.
> > > > > > Releasing dc_sink should be binding with the disconnection event.
> > > > > >
> > > > > > I understand your concern that we should not just easily change
> > > > > > the
> > > > > > logic here since it's the result after solving tons of bugs before
> > > > > > and might cause other side effect. So, just my 2 cents, what I'm
> > > > > > thinking is to register a callback function for our driver to
> > > > > > notify
> > > > > > us that the remote sink is detached. This just aligns our flow
> > > > > > handling long HPD event of legacy (sst) DP.
> > > > > > For sst case, once we detect long HPD event indicating the monitor
> > > > > > is detached, we will immediately try to release the
> > > > > > dc_link->local_sink and fire hotplug event to upper layer. Same as
> > > > > > here, once receives a CSN message notifying a drm connector is
> > > > > > changed from connected to disconnected, trigger the callback
> > > > > > function and we can try to release the dc_sink resource.
> > > > > >
> > > > > > Would like to know your thought and insight please : )
> > > > > >
> > > > > > Btw, I got some errors and warnings while building and have some
> > > > > > code adjustments as below : ) Thank you Lyude for your always
> > > > > > kindly
> > > > > > help!!
> > > > > >
> > > > > > Regards,
> > > > > > Wayne
> > > > > > > -----Original Message-----
> > > > > > > From: Lyude Paul <lyude@xxxxxxxxxx>
> > > > > > > Sent: Wednesday, November 3, 2021 7:15 AM
> > > > > > > To: Lin, Wayne <Wayne.Lin@xxxxxxx>
> > > > > > > Subject: [PATCH] WIP: drm/dp_mst: Add support for dumping
> > > > > > > topology
> > > > > > > ref histories from debugfs
> > > > > > >
> > > > > > > TODO:
> > > > > > > * Implement support for i915
> > > > > > > * Finish writing this commit message
> > > > > > > * ???
> > > > > > > * profit
> > > > > > >
> > > > > > > Signed-off-by: Lyude Paul <lyude@xxxxxxxxxx>
> > > > > > > ---
> > > > > > >
> > > > > > > Hey wayne! SO-hopefully if I did this correctly then this should
> > > > > > > just work on amdgpu. What this patch should do is add a debugfs
> > > > > > > file to amdgpu called "amdgpu_dp_mst_topology_refs", and when
> > > > > > > you
> > > > > > > read the file it should print out the topology reference history
> > > > > > > of every MSTB and Port in memory, along with how many times
> > > > > > > we've
> > > > > > > hit the codepath in each backtrace. An example:
> > > > > > >
> > > > > > > Port DP-5 (0000000005c37748) topology ref history:
> > > > > > > 1 gets (last at 58.468973):
> > > > > > > drm_dp_send_link_address+0x6a5/0xa00 [drm_kms_helper]
> > > > > > > drm_dp_check_and_send_link_address+0xad/0xd0
> > > > > > > [drm_kms_helper]
> > > > > > > drm_dp_mst_link_probe_work+0x14e/0x1a0 [drm_kms_helper]
> > > > > > > process_one_work+0x1e3/0x390
> > > > > > > worker_thread+0x50/0x3a0
> > > > > > > kthread+0x124/0x150
> > > > > > > ret_from_fork+0x1f/0x30
> > > > > > > 1 puts (last at 58.469357):
> > > > > > > drm_dp_mst_topology_put_port+0x6a/0x210 [drm_kms_helper]
> > > > > > > drm_dp_send_link_address+0x39e/0xa00 [drm_kms_helper]
> > > > > > > drm_dp_check_and_send_link_address+0xad/0xd0
> > > > > > > [drm_kms_helper]
> > > > > > > drm_dp_mst_link_probe_work+0x14e/0x1a0 [drm_kms_helper]
> > > > > > > process_one_work+0x1e3/0x390
> > > > > > > worker_thread+0x50/0x3a0
> > > > > > > kthread+0x124/0x150
> > > > > > > ret_from_fork+0x1f/0x30
> > > > > > >
> > > > > > > The idea here is that if stream resources aren't being released,
> > > > > > > my guess would be that we're not dropping topology references
> > > > > > > for
> > > > > > > the port which means the connector never goes away. So, if
> > > > > > > that's
> > > > > > > really the case then once we unplug the offending connector we
> > > > > > > should be able to find a pair of gets/puts for the offending
> > > > > > > leaked connector where the get/put count doesn't match up. Also,
> > > > > > > if the frame count on the backtrace isn't long enough you can
> > > > > > > increase the value of STACK_DEPTH in
> > > > > > > drivers/gpu/drm/drm_dp_mst_topology.c and recompile to get more
> > > > > > > frames.
> > > > > > >
> > > > > > > To enable this, first enable CONFIG_EXPERT for your kernel which
> > > > > > > will unhide CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS. Then just
> > > > > > > enable CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS, recompile, and it
> > > > > > > should be good to go.
> > > > > > >
> > > > > > > Let me know if this works for you, and hopefully this should
> > > > > > > tell
> > > > > > > us exactly what the problem actually is here.
> > > > > > >
> > > > > > > .../amd/display/amdgpu_dm/amdgpu_dm_debugfs.c | 35 ++++
> > > > > > > drivers/gpu/drm/drm_dp_mst_topology.c | 173
> > > > > > > ++++++++++++++----
> > > > > > > drivers/gpu/drm/nouveau/nouveau_debugfs.c | 35 ++++
> > > > > > > include/drm/drm_dp_mst_helper.h | 18 ++
> > > > > > > 4 files changed, 228 insertions(+), 33 deletions(-)
> > > > > > >
> > > > > > >
> > > > > > > diff --git
> > > > > > > a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c
> > > > > > > b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c
> > > > > > > index 1a68a674913c..1a14732c52b4 100644
> > > > > > > --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c
> > > > > > > +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c
> > > > > > > @@ -3063,6 +3063,37 @@ static int mst_topo_show(struct seq_file
> > > > > > > *m, void
> > > > > > > *unused)
> > > > > > > return 0;
> > > > > > > }
> > > > > > >
> > > > > > > +#ifdef CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS
> > > > > > > +static int mst_topology_ref_dump_show(struct seq_file *m, void
> > > > > > > +*unused) {
> > > > > > > + struct amdgpu_device *adev = (struct amdgpu_device
> > > > > > > +*)m->private;
> > > > > > > + struct drm_device *dev = adev_to_drm(adev);
> > > > > > > + struct drm_connector *connector;
> > > > > > > + struct drm_connector_list_iter conn_iter;
> > > > > > > + struct amdgpu_dm_connector *aconnector;
> > > > > > > +
> > > > > > > + drm_connector_list_iter_begin(dev, &conn_iter);
> > > > > > > + drm_for_each_connector_iter(connector, &conn_iter) {
> > > > > > > + if (connector->connector_type !=
> > > > > > > DRM_MODE_CONNECTOR_DisplayPort)
> > > > > > > + continue;
> > > > > > > +
> > > > > > > + aconnector = to_amdgpu_dm_connector(connector);
> > > > > > > +
> > > > > > > + /* Ensure we're only dumping the topology of a
> > > > > > > root
> > > > > > > +mst node
> > > > > > > */
> > > > > > > + if (!aconnector->mst_mgr.max_payloads)
> > > > > > > + continue;
> > > > > > > +
> > > > > > > + seq_printf(m, "\nMST topology for connector %d\n",
> > > > > > > aconnector->connector_id);
> > > > > > > + drm_dp_mst_dump_topology_refs(m,
> > > > > > > +&aconnector->mst_mgr);
> > > > > > > + }
> > > > > > > + drm_connector_list_iter_end(&conn_iter);
> > > > > > > +
> > > > > > > + return 0;
> > > > > > > +}
> > > > > > > +
> > > > > > > +DEFINE_SHOW_ATTRIBUTE(mst_topology_ref_dump);
> > > > > > > +#endif
> > > > > > > +
> > > > > > > /*
> > > > > > > * Sets trigger hpd for MST topologies.
> > > > > > > * All connected connectors will be rediscovered and re started
> > > > > > > as needed if val of 1 is sent.
> > > > > > > @@ -3299,6 +3330,10 @@ void dtn_debugfs_init(struct
> > > > > > > amdgpu_device
> > > > > > > *adev)
> > > > > > >
> > > > > > > debugfs_create_file("amdgpu_mst_topology", 0444, root,
> > > > > > > adev, &mst_topo_fops);
> > > > > > > +#ifdef CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS
> > > > > > > + debugfs_create_file("amdgpu_dp_mst_topology_refs", 0444,
> > > > > > > +root, adev,
> > > > > > > + &mst_topology_ref_dump_fops); #endif
> > > > > > > debugfs_create_file("amdgpu_dm_dtn_log", 0644, root, adev,
> > > > > > > &dtn_log_fops);
> > > > > > >
> > > > > > > diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c
> > > > > > > b/drivers/gpu/drm/drm_dp_mst_topology.c
> > > > > > > index 1aa8702383d4..0159828c494d 100644
> > > > > > > --- a/drivers/gpu/drm/drm_dp_mst_topology.c
> > > > > > > +++ b/drivers/gpu/drm/drm_dp_mst_topology.c
> > > > > > > @@ -1366,23 +1366,6 @@ static int
> > > > > > > drm_dp_mst_wait_tx_reply(struct
> > > > > > > drm_dp_mst_branch *mstb,
> > > > > > > return ret;
> > > > > > > }
> > > > > > >
> > > > > > > -static struct drm_dp_mst_branch
> > > > > > > *drm_dp_add_mst_branch_device(u8
> > > > > > > lct, u8
> > > > > > > *rad) -{
> > > > > > > - struct drm_dp_mst_branch *mstb;
> > > > > > > -
> > > > > > > - mstb = kzalloc(sizeof(*mstb), GFP_KERNEL);
> > > > > > > - if (!mstb)
> > > > > > > - return NULL;
> > > > > > > -
> > > > > > > - mstb->lct = lct;
> > > > > > > - if (lct > 1)
> > > > > > > - memcpy(mstb->rad, rad, lct / 2);
> > > > > > > - INIT_LIST_HEAD(&mstb->ports);
> > > > > > > - kref_init(&mstb->topology_kref);
> > > > > > > - kref_init(&mstb->malloc_kref);
> > > > > > > - return mstb;
> > > > > > > -}
> > > > > > > -
> > > > > > > static void drm_dp_free_mst_branch_device(struct kref *kref) {
> > > > > > > struct drm_dp_mst_branch *mstb = @@ -1642,12 +1625,20 @@
> > > > > > > topology_ref_type_to_str(enum drm_dp_mst_topology_ref_type type)
> > > > > > > return "put";
> > > > > > > }
> > > > > > >
> > > > > > > +static const char *topology_ref_history_type_to_str(enum
> > > > > > > +drm_dp_mst_topology_history_type type) {
> > > > > > > + if (type == DRM_DP_MST_TOPOLOGY_HISTORY_PORT)
> > > > > > > + return "Port";
> > > > > > > + else
> > > > > > > + return "MSTB";
> > > > > > > +}
> > > > > > > +
> > > > > > > static void
> > > > > > > -__dump_topology_ref_history(struct
> > > > > > > drm_dp_mst_topology_ref_history *history,
> > > > > > > - void *ptr, const char *type_str)
> > > > > > > +dump_topology_ref_history(struct
> > > > > > > drm_dp_mst_topology_ref_history
> > > > > > > +*history, struct drm_printer p)
> > > > > > > {
> > > > > > > - struct drm_printer p = drm_debug_printer(DBG_PREFIX);
> > > > > > > + char *connector_name = NULL;
> > > > > > > char *buf = kzalloc(PAGE_SIZE, GFP_KERNEL);
> > > > > > > + void *ptr;
> > > > > > > int i;
> > > > > > >
> > > > > > > if (!buf)
> > > > > > > @@ -1656,14 +1647,29 @@ __dump_topology_ref_history(struct
> > > > > > > drm_dp_mst_topology_ref_history *history,
> > > > > > > if (!history->len)
> > > > > > > goto out;
> > > > > > >
> > > > > > > + /* Get a pointer to the actual MSTB/port so we can the
> > > > > > > +memory
> > > > > > > address to the kernel log */
> > > > > > > + if (history->type == DRM_DP_MST_TOPOLOGY_HISTORY_PORT)
> > > > > > > + ptr = container_of(history, struct
> > > > > > > drm_dp_mst_port,
> > > > > > > topology_ref_history);
> > > > > > > + else
> > > > > > > + ptr = container_of(history, struct
> > > > > > > +drm_dp_mst_branch, topology_ref_history);
> > > > > > > +
> > > > > > > /* First, sort the list so that it goes from oldest to
> > > > > > > newest
> > > > > > > * reference entry
> > > > > > > */
> > > > > > > sort(history->entries, history->len,
> > > > > > > sizeof(*history->entries),
> > > > > > > topology_ref_history_cmp, NULL);
> > > > > > >
> > > > > > > - drm_printf(&p, "%s (%p) topology count reached 0, dumping
> > > > > > > history:\n",
> > > > > > > - type_str, ptr);
> > > > > > > + if (history->type == DRM_DP_MST_TOPOLOGY_HISTORY_PORT) {
> > > > > > > + struct drm_dp_mst_port *port = ptr;
> > > > > > > +
> > > > > > > + if (port->connector)
> > > > > > > + connector_name = port->connector->name;
> > > > > > > + }
> > > > > > > + if (connector_name)
> > > > > > > + drm_printf(&p, "Port %s (%p) topology ref
> > > > > > > +history:\n",
> > > > > > > connector_name, ptr);
> > > > > > > + else
> > > > > > > + drm_printf(&p, "%s (%p) topology ref history:\n",
> > > > > > > +
> > > > > > > +topology_ref_history_type_to_str(history->type),
> > > > > > > ptr);
> > > > > > >
> > > > > > > for (i = 0; i < history->len; i++) {
> > > > > > > const struct drm_dp_mst_topology_ref_entry *entry
> > > > > > > =
> > > > > > > @@
> > > > > > > -
> > > > > > > 1682,24 +1688,92 @@ __dump_topology_ref_history(struct
> > > > > > > drm_dp_mst_topology_ref_history *history,
> > > > > > > ts_nsec, rem_nsec / 1000, buf);
> > > > > > > }
> > > > > > >
> > > > > > > - /* Now free the history, since this is the only time we
> > > > > > > expose it */
> > > > > > > - kfree(history->entries);
> > > > > > > out:
> > > > > > > kfree(buf);
> > > > > > > }
> > > > > > >
> > > > > > > +/**
> > > > > > > + * drm_dp_mst_dump_topology_refs - helper function for dumping
> > > > > > > +the topology ref history
> > > > > > > + * @m: File to print to
> > > > > > > + * @mgr: &struct drm_dp_mst_topology_mgr to use
> > > > > > > + *
> > > > > > > + * Prints the topology ref history of all ports and MSTBs on
> > > > > > > @mgr
> > > > > > > +that are still in memory,
> > > > > > > + * regardless of whether they're actually still reachable
> > > > > > > through
> > > > > > > +the topology or not. Only enabled
> > > > > > > + * when %CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS is enabled. Can
> > > > > > > be
> > > > > > > +implemented by drivers to assist
> > > > > > > + * with debugging leaks in the DP MST helpers.
> > > > > > > + */
> > > > > > > +void drm_dp_mst_dump_topology_refs(struct seq_file *m, struct
> > > > > > > +drm_dp_mst_topology_mgr *mgr) {
> > > > > > > + struct drm_dp_mst_topology_ref_history *history;
> > > > > > > + struct drm_printer p = drm_seq_file_printer(m);
> > > > > > > +
> > > > > > > + mutex_lock(&mgr->topology_ref_history_lock);
> > > > > > > + list_for_each_entry(history,
> > > > > > > +&mgr->topology_ref_history_list,
> > > > > > > +node)
> > > > > > > + dump_topology_ref_history(history, p);
> > > > > > > + mutex_unlock(&mgr->topology_ref_history_lock);
> > > > > > > +}
> > > > > > > +EXPORT_SYMBOL(drm_dp_mst_dump_topology_refs);
> > > > > > > +
> > > > > > > +static void
> > > > > > > +__init_topology_ref_history(struct
> > > > > > > +drm_dp_mst_topology_ref_history
> > > > > > > *history,
> > > > > > > + struct drm_dp_mst_topology_mgr *mgr,
> > > > > > > + enum drm_dp_mst_topology_history_type
> > > > > > > +type) {
> > > > > > > + history->type = type;
> > > > > > > + INIT_LIST_HEAD(&history->node);
> > > > > > > +
> > > > > > > + mutex_lock(&mgr->topology_ref_history_lock);
> > > > > > > + list_add(&history->node, &mgr->topology_ref_history_list);
> > > > > > > + mutex_unlock(&mgr->topology_ref_history_lock);
> > > > > > > +}
> > > > > > > +
> > > > > > > +static void
> > > > > > > +__destroy_topology_ref_history(struct
> > > > > > > +drm_dp_mst_topology_ref_history
> > > > > > > *history,
> > > > > > > + struct drm_dp_mst_topology_mgr
> > > > > > > *mgr)
> > > > > > > +{
> > > > > > > + mutex_lock(&mgr->topology_ref_history_lock);
> > > > > > > + list_del(&mgr->topology_ref_history_list);
> > > > > > > + mutex_unlock(&mgr->topology_ref_history_lock);
> > > > > > > +
> > > > > > > + kfree(history->entries);
> > > > > > > +}
> > > > > > > +
> > > > > > > +static __always_inline void
> > > > > > > +init_port_topology_history(struct drm_dp_mst_topology_mgr *mgr,
> > > > > > > +struct drm_dp_mst_port *port) {
> > > > > > > + __init_topology_ref_history(&port->topology_ref_history,
> > > > > > > +mgr,
> > > > > > > +
> > > > > > > +DRM_DP_MST_TOPOLOGY_HISTORY_PORT);
> > > > > > > +}
> > > > > > > +
> > > > > > > +static __always_inline void
> > > > > > > +init_mstb_topology_history(struct drm_dp_mst_topology_mgr *mgr,
> > > > > > > +struct drm_dp_mst_branch *mstb) {
> > > > > > > + __init_topology_ref_history(&mstb->topology_ref_history,
> > > > > > > +mgr,
> > > > > > > +
> > > > > > > +DRM_DP_MST_TOPOLOGY_HISTORY_MSTB);
> > > > > > > +}
> > > > > > > +
> > > > > > > +static __always_inline void
> > > > > > > +destroy_port_topology_history(struct drm_dp_mst_port *port) {
> > > > > > > + __destroy_topology_ref_history(&port-
> > > > > > > >topology_ref_history,
> > > > > > > +port->mgr); }
> > > > > > > +
> > > > > > > +static __always_inline void
> > > > > > > +destroy_mstb_topology_history(struct drm_dp_mst_branch *mstb) {
> > > > > > > + __destroy_topology_ref_history(&mstb-
> > > > > > > >topology_ref_history,
> > > > > > > +mstb->mgr); }
> > > > > > > +
> > > > > > > static __always_inline void
> > > > > > > dump_mstb_topology_history(struct drm_dp_mst_branch *mstb) {
> > > > > > > - __dump_topology_ref_history(&mstb->topology_ref_history,
> > > > > > > mstb,
> > > > > > > - "MSTB");
> > > > > > > + dump_topology_ref_history(&mstb->topology_ref_history,
> > > > > > > +drm_debug_printer(DBG_PREFIX));
> > > > > > > }
> > > > > > >
> > > > > > > static __always_inline void
> > > > > > > dump_port_topology_history(struct drm_dp_mst_port *port) {
> > > > > > > - __dump_topology_ref_history(&port->topology_ref_history,
> > > > > > > port,
> > > > > > > - "Port");
> > > > > > > + dump_topology_ref_history(&port->topology_ref_history,
> > > > > > > +drm_debug_printer(DBG_PREFIX));
> > > > > > > }
> > > > > > >
> > > > > > > static __always_inline void
> > > > > > > @@ -1729,6 +1803,14 @@ topology_ref_history_unlock(struct
> > > > > > > drm_dp_mst_topology_mgr *mgr) } #else static inline void
> > > > > > > +init_port_topology_history(struct drm_dp_mst_topology_mgr *mgr,
> > > > > > > +struct drm_dp_mst_port *port); static inline void
> > > > > > Should also add the bracket, otherwise will get warnings.
> > > > > > => static inline void init_port_topology_history(struct
> > > > > > drm_dp_mst_topology_mgr *mgr, struct drm_dp_mst_port *port) {};
> > > > > >
> > > > > > > +init_mstb_topology_history(struct drm_dp_mst_topology_mgr *mgr,
> > > > > > > +struct drm_dp_mst_branch *mstb); static inline void
> > > > > > Same as above
> > > > > > => static inline void init_mstb_topology_history(struct
> > > > > > drm_dp_mst_topology_mgr *mgr, struct drm_dp_mst_branch *mstb) {};
> > > > > >
> > > > > > > +destroy_port_topology_history(struct drm_dp_mst_topology_mgr
> > > > > > > +*mgr, struct drm_dp_mst_port *port); static inline void
> > > > > > destroy_port_topology_history() takes one parameter only which is
> > > > > > port.
> > > > > > => destroy_port_topology_history(struct drm_dp_mst_port *port) {};
> > > > > >
> > > > > > > +destroy_mstb_topology_history(struct drm_dp_mst_topology_mgr
> > > > > > > +*mgr, struct drm_dp_mst_branch *mstb); static inline void
> > > > > > destroy_mstb_topology_history() takes one parameter only which is
> > > > > > mstb => destroy_mstb_topology_history(struct drm_dp_mst_branch
> > > > > > *mstb) {};
> > > > > >
> > > > > > > topology_ref_history_lock(struct drm_dp_mst_topology_mgr *mgr)
> > > > > > > {}
> > > > > > > static inline void topology_ref_history_unlock(struct
> > > > > > > drm_dp_mst_topology_mgr *mgr) {} @@ -1740,6 +1822,25 @@
> > > > > > > dump_port_topology_history(struct drm_dp_mst_port *port) {}
> > > > > > > #define save_port_topology_ref(port, type) #endif
> > > > > > >
> > > > > > > +static struct drm_dp_mst_branch *
> > > > > > > +drm_dp_add_mst_branch_device(struct drm_dp_mst_topology_mgr
> > > > > > > *mgr,
> > > > > > > +u8 lct, u8 *rad) {
> > > > > > > + struct drm_dp_mst_branch *mstb;
> > > > > > > +
> > > > > > > + mstb = kzalloc(sizeof(*mstb), GFP_KERNEL);
> > > > > > > + if (!mstb)
> > > > > > > + return NULL;
> > > > > > > +
> > > > > > > + mstb->lct = lct;
> > > > > > > + if (lct > 1)
> > > > > > > + memcpy(mstb->rad, rad, lct / 2);
> > > > > > > + INIT_LIST_HEAD(&mstb->ports);
> > > > > > > + kref_init(&mstb->topology_kref);
> > > > > > > + kref_init(&mstb->malloc_kref);
> > > > > > > + init_mstb_topology_history(mgr, mstb);
> > > > > > > + return mstb;
> > > > > > > +}
> > > > > > > +
> > > > > > > static void drm_dp_destroy_mst_branch_device(struct kref *kref)
> > > > > > > {
> > > > > > > struct drm_dp_mst_branch *mstb = @@ -1747,6 +1848,7 @@
> > > > > > > static void drm_dp_destroy_mst_branch_device(struct
> > > > > > > kref *kref)
> > > > > > > struct drm_dp_mst_topology_mgr *mgr = mstb->mgr;
> > > > > > >
> > > > > > > dump_mstb_topology_history(mstb);
> > > > > > > + destroy_mstb_topology_history(mstb);
> > > > > > >
> > > > > > > INIT_LIST_HEAD(&mstb->destroy_next);
> > > > > > >
> > > > > > > @@ -1856,6 +1958,7 @@ static void drm_dp_destroy_port(struct
> > > > > > > kref
> > > > > > > *kref)
> > > > > > > struct drm_dp_mst_topology_mgr *mgr = port->mgr;
> > > > > > >
> > > > > > > dump_port_topology_history(port);
> > > > > > > + destroy_port_topology_history(port);
> > > > > > >
> > > > > > > /* There's nothing that needs locking to destroy an input
> > > > > > > port yet */
> > > > > > > if (port->input) {
> > > > > > > @@ -2135,7 +2238,7 @@ drm_dp_port_set_pdt(struct drm_dp_mst_port
> > > > > > > *port, u8 new_pdt,
> > > > > > > ret = drm_dp_mst_register_i2c_bus(port);
> > > > > > > } else {
> > > > > > > lct = drm_dp_calculate_rad(port, rad);
> > > > > > > - mstb = drm_dp_add_mst_branch_device(lct,
> > > > > > > rad);
> > > > > > > + mstb = drm_dp_add_mst_branch_device(mgr,
> > > > > > > +lct, rad);
> > > > > > > if (!mstb) {
> > > > > > > ret = -ENOMEM;
> > > > > > > drm_err(mgr->dev, "Failed to
> > > > > > > create
> > > > > > > MSTB for port %p", port); @@ -2366,6 +2469,8 @@
> > > > > > > drm_dp_mst_add_port(struct drm_device *dev,
> > > > > > > */
> > > > > > > drm_dp_mst_get_mstb_malloc(mstb);
> > > > > > >
> > > > > > > + init_port_topology_history(mgr, port);
> > > > > > > +
> > > > > > > return port;
> > > > > > > }
> > > > > > >
> > > > > > > @@ -3745,7 +3850,7 @@ int drm_dp_mst_topology_mgr_set_mst(struct
> > > > > > > drm_dp_mst_topology_mgr *mgr, bool ms
> > > > > > > }
> > > > > > >
> > > > > > > /* add initial branch device at LCT 1 */
> > > > > > > - mstb = drm_dp_add_mst_branch_device(1, NULL);
> > > > > > > + mstb = drm_dp_add_mst_branch_device(mgr, 1, NULL);
> > > > > > > if (mstb == NULL) {
> > > > > > > ret = -ENOMEM;
> > > > > > > goto out_unlock; @@ -5512,14 +5617,16 @@
> > > > > > > int
> > > > > > > drm_dp_mst_topology_mgr_init(struct
> > > > > > > drm_dp_mst_topology_mgr *mgr,
> > > > > > > mutex_init(&mgr->delayed_destroy_lock);
> > > > > > > mutex_init(&mgr->up_req_lock);
> > > > > > > mutex_init(&mgr->probe_lock); -#if
> > > > > > > IS_ENABLED(CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS)
> > > > > > > - mutex_init(&mgr->topology_ref_history_lock);
> > > > > > > -#endif
> > > > > > > INIT_LIST_HEAD(&mgr->tx_msg_downq);
> > > > > > > INIT_LIST_HEAD(&mgr->destroy_port_list);
> > > > > > > INIT_LIST_HEAD(&mgr->destroy_branch_device_list);
> > > > > > > INIT_LIST_HEAD(&mgr->up_req_list);
> > > > > > >
> > > > > > > +#if IS_ENABLED(CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS)
> > > > > > > + mutex_init(&mgr->topology_ref_history_lock);
> > > > > > > + INIT_LIST_HEAD(&mgr->topology_ref_history_list);
> > > > > > > +#endif
> > > > > > > +
> > > > > > > /*
> > > > > > > * delayed_destroy_work will be queued on a dedicated WQ,
> > > > > > > so
> > > > > > > that any
> > > > > > > * requeuing will be also flushed when deiniting the
> > > > > > > topology manager.
> > > > > > > diff --git a/drivers/gpu/drm/nouveau/nouveau_debugfs.c
> > > > > > > b/drivers/gpu/drm/nouveau/nouveau_debugfs.c
> > > > > > > index 1cbe01048b93..53ec7c1daada 100644
> > > > > > > --- a/drivers/gpu/drm/nouveau/nouveau_debugfs.c
> > > > > > > +++ b/drivers/gpu/drm/nouveau/nouveau_debugfs.c
> > > > > > > @@ -29,9 +29,13 @@
> > > > > > > */
> > > > > > >
> > > > > > > #include <linux/debugfs.h>
> > > > > > > +#include <drm/drm_dp_mst_helper.h> #include <drm/drm_encoder.h>
> > > > > > > #include <nvif/class.h>
> > > > > > > #include <nvif/if0001.h>
> > > > > > > +#include <nouveau_encoder.h>
> > > > > > > #include "nouveau_debugfs.h"
> > > > > > > +#include "nouveau_display.h"
> > > > > > > #include "nouveau_drv.h"
> > > > > > >
> > > > > > > static int
> > > > > > > @@ -68,6 +72,34 @@ nouveau_debugfs_strap_peek(struct seq_file
> > > > > > > *m,
> > > > > > > void
> > > > > > > *data)
> > > > > > > return 0;
> > > > > > > }
> > > > > > >
> > > > > > > +#ifdef CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS
> > > > > > > +static int nouveau_debugfs_mst_topology_history(struct seq_file
> > > > > > > +*m, void *data) {
> > > > > > > + struct drm_info_node *node = m->private;
> > > > > > > + struct drm_device *dev = node->minor->dev;
> > > > > > > + struct drm_encoder *encoder;
> > > > > > > + struct nouveau_display *disp = nouveau_display(dev);
> > > > > > > +
> > > > > > > + if (disp->disp.object.oclass < GF110_DISP)
> > > > > > > + return -EINVAL;
> > > > > > > +
> > > > > > > + drm_for_each_encoder(encoder, dev) {
> > > > > > > + struct nv50_mstm *mstm;
> > > > > > > +
> > > > > > > + /* We need the real encoder for each MST mgr */
> > > > > > > + if (encoder->encoder_type !=
> > > > > > > DRM_MODE_ENCODER_TMDS)
> > > > > > > + continue;
> > > > > > > + mstm = nouveau_encoder(encoder)->dp.mstm;
> > > > > > > + if (!mstm)
> > > > > > > + continue;
> > > > > > > +
> > > > > > > + seq_printf(m, "MSTM on %s:\n", encoder->name);
> > > > > > > + drm_dp_mst_dump_topology_refs(m, &mstm->mgr);
> > > > > > > + }
> > > > > > > + return 0;
> > > > > > > +}
> > > > > > > +#endif
> > > > > > > +
> > > > > > > static int
> > > > > > > nouveau_debugfs_pstate_get(struct seq_file *m, void *data) {
> > > > > > > @@
> > > > > > > -213,6
> > > > > > > +245,9 @@ static const struct file_operations
> > > > > > > nouveau_pstate_fops = { static struct drm_info_list
> > > > > > > nouveau_debugfs_list[] = {
> > > > > > > { "vbios.rom", nouveau_debugfs_vbios_image, 0, NULL },
> > > > > > > { "strap_peek", nouveau_debugfs_strap_peek, 0, NULL },
> > > > > > > +#ifdef CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS
> > > > > > > + { "dp_mst_topology_refs",
> > > > > > > +nouveau_debugfs_mst_topology_history, 0, NULL }, #endif
> > > > > > > };
> > > > > > > #define NOUVEAU_DEBUGFS_ENTRIES
> > > > > > > ARRAY_SIZE(nouveau_debugfs_list)
> > > > > > >
> > > > > > > diff --git a/include/drm/drm_dp_mst_helper.h
> > > > > > > b/include/drm/drm_dp_mst_helper.h index
> > > > > > > 78044ac5b59b..e3a73d8d97c0
> > > > > > > 100644
> > > > > > > --- a/include/drm/drm_dp_mst_helper.h
> > > > > > > +++ b/include/drm/drm_dp_mst_helper.h
> > > > > > > @@ -35,6 +35,11 @@ enum drm_dp_mst_topology_ref_type {
> > > > > > > DRM_DP_MST_TOPOLOGY_REF_PUT,
> > > > > > > };
> > > > > > >
> > > > > > > +enum drm_dp_mst_topology_history_type {
> > > > > > > + DRM_DP_MST_TOPOLOGY_HISTORY_PORT,
> > > > > > > + DRM_DP_MST_TOPOLOGY_HISTORY_MSTB, };
> > > > > > > +
> > > > > > > struct drm_dp_mst_topology_ref_history {
> > > > > > > struct drm_dp_mst_topology_ref_entry {
> > > > > > > enum drm_dp_mst_topology_ref_type type; @@ -43,6
> > > > > > > +48,9 @@ struct drm_dp_mst_topology_ref_history {
> > > > > > > depot_stack_handle_t backtrace;
> > > > > > > } *entries;
> > > > > > > int len;
> > > > > > > +
> > > > > > > + enum drm_dp_mst_topology_history_type type;
> > > > > > > + struct list_head node;
> > > > > > > };
> > > > > > > #endif /* IS_ENABLED(CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS) */
> > > > > > >
> > > > > > > @@ -769,6 +777,12 @@ struct drm_dp_mst_topology_mgr {
> > > > > > > * &drm_dp_mst_branch.topology_ref_history.
> > > > > > > */
> > > > > > > struct mutex topology_ref_history_lock;
> > > > > > > +
> > > > > > > + /**
> > > > > > > + * @topology_ref_history_list: contains a list of topology
> > > > > > > +ref
> > > > > > > histories for any MSTBs or
> > > > > > > + * ports that are still in memory
> > > > > > > + */
> > > > > > > + struct list_head topology_ref_history_list;
> > > > > > > #endif
> > > > > > > };
> > > > > > >
> > > > > > > @@ -873,6 +887,10 @@ void drm_dp_mst_put_port_malloc(struct
> > > > > > > drm_dp_mst_port *port);
> > > > > > >
> > > > > > > struct drm_dp_aux *drm_dp_mst_dsc_aux_for_port(struct
> > > > > > > drm_dp_mst_port *port);
> > > > > > >
> > > > > > > +#ifdef CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS
> > > > > > > +void drm_dp_mst_dump_topology_refs(struct seq_file *m, struct
> > > > > > > +drm_dp_mst_topology_mgr *mgr); #endif
> > > > > > > +
> > > > > > > extern const struct drm_private_state_funcs
> > > > > > > drm_dp_mst_topology_state_funcs;
> > > > > > >
> > > > > > > /**
> > > > > > > --
> > > > > > > 2.31.1
> > > > > >
> > > > >
> > > > > --
> > > > > Cheers,
> > > > > Lyude Paul (she/her)
> > > > > Software Engineer at Red Hat
> > >
> >
>
--
Cheers,
Lyude Paul (she/her)
Software Engineer at Red Hat
