On Tue, Jan 31, 2023 at 06:13:10PM -0500, Lyude Paul wrote:
> On Tue, 2023-01-31 at 17:05 +0200, Imre Deak wrote:
> > Atm, drm_dp_remove_payload() uses the same payload state to both get the
> > vc_start_slot required for the payload removal DPCD message and to
> > deduct time_slots from vc_start_slot of all payloads after the one being
> > removed.
> >
> > The above isn't always correct, as vc_start_slot must be the up-to-date
> > version contained in the new payload state, but time_slots must be the
> > one used when the payload was previously added, contained in the old
> > payload state. The new payload's time_slots can change vs. the old one
> > if the current atomic commit changes the corresponding mode.
> >
> > This patch let's drivers pass the old and new payload states to
> > drm_dp_remove_payload(), but keeps these the same for now in all drivers
> > not to change the behavior. A follow-up i915 patch will pass in that
> > driver the correct old and new states to the function.
>
> Oh wow, this was definitely a mistake on my part, thanks for catching this!
> TBH, I think this behavior is correct so (now that I actually have a setup
> capable of testing amdgpu's MST fully thanks to gitlab issue 2171…) if you'd
> like to change it on other drivers as well I can test it fully.
I only checked that the other drivers pass the new payload state to
drm_dp_remove_payload(), so not sure how that works atm if the same
commit has to both remove the payload (with the old time_slots value)
and add it back (with a new time_slots value). Maybe that can't happen
in those drivers, or time_slots get updated between remove and readd.
> Or feel free to leave it to me, shouldn't be too difficult I think :).
Yes, this patch should have no functional change, so please check what
would apply to other drivers as well.
Could you also check Ville's comment about storing start_slot elsewhere
than the atomic state (leaving only time_slots there). I wonder if that
would work, at least it would simplify things I think.
> For 0-2:
>
> Reviewed-by: Lyude Paul <lyude@xxxxxxxxxx>
Thanks.
>
> >
> > Cc: Lyude Paul <lyude@xxxxxxxxxx>
> > Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> > Cc: Ben Skeggs <bskeggs@xxxxxxxxxx>
> > Cc: Karol Herbst <kherbst@xxxxxxxxxx>
> > Cc: Harry Wentland <harry.wentland@xxxxxxx>
> > Cc: Alex Deucher <alexander.deucher@xxxxxxx>
> > Cc: Wayne Lin <Wayne.Lin@xxxxxxx>
> > Cc: stable@xxxxxxxxxxxxxxx # 6.1
> > Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx
> > Reviewed-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> > Signed-off-by: Imre Deak <imre.deak@xxxxxxxxx>
> > ---
> > .../amd/display/amdgpu_dm/amdgpu_dm_helpers.c | 2 +-
> > drivers/gpu/drm/display/drm_dp_mst_topology.c | 26 ++++++++++---------
> > drivers/gpu/drm/i915/display/intel_dp_mst.c | 4 ++-
> > drivers/gpu/drm/nouveau/dispnv50/disp.c | 2 +-
> > include/drm/display/drm_dp_mst_helper.h | 3 ++-
> > 5 files changed, 21 insertions(+), 16 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
> > index a50319fc42b11..180d3893b68da 100644
> > --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
> > +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
> > @@ -208,7 +208,7 @@ bool dm_helpers_dp_mst_write_payload_allocation_table(
> > if (enable)
> > drm_dp_add_payload_part1(mst_mgr, mst_state, payload);
> > else
> > - drm_dp_remove_payload(mst_mgr, mst_state, payload);
> > + drm_dp_remove_payload(mst_mgr, mst_state, payload, payload);
> >
> > /* mst_mgr->->payloads are VC payload notify MST branch using DPCD or
> > * AUX message. The sequence is slot 1-63 allocated sequence for each
> > diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c b/drivers/gpu/drm/display/drm_dp_mst_topology.c
> > index 847c10aa2098c..1990ff5dc7ddd 100644
> > --- a/drivers/gpu/drm/display/drm_dp_mst_topology.c
> > +++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c
> > @@ -3342,7 +3342,8 @@ EXPORT_SYMBOL(drm_dp_add_payload_part1);
> > * drm_dp_remove_payload() - Remove an MST payload
> > * @mgr: Manager to use.
> > * @mst_state: The MST atomic state
> > - * @payload: The payload to write
> > + * @old_payload: The payload with its old state
> > + * @new_payload: The payload to write
> > *
> > * Removes a payload from an MST topology if it was successfully assigned a start slot. Also updates
> > * the starting time slots of all other payloads which would have been shifted towards the start of
> > @@ -3350,36 +3351,37 @@ EXPORT_SYMBOL(drm_dp_add_payload_part1);
> > */
> > void drm_dp_remove_payload(struct drm_dp_mst_topology_mgr *mgr,
> > struct drm_dp_mst_topology_state *mst_state,
> > - struct drm_dp_mst_atomic_payload *payload)
> > + const struct drm_dp_mst_atomic_payload *old_payload,
> > + struct drm_dp_mst_atomic_payload *new_payload)
> > {
> > struct drm_dp_mst_atomic_payload *pos;
> > bool send_remove = false;
> >
> > /* We failed to make the payload, so nothing to do */
> > - if (payload->vc_start_slot == -1)
> > + if (new_payload->vc_start_slot == -1)
> > return;
> >
> > mutex_lock(&mgr->lock);
> > - send_remove = drm_dp_mst_port_downstream_of_branch(payload->port, mgr->mst_primary);
> > + send_remove = drm_dp_mst_port_downstream_of_branch(new_payload->port, mgr->mst_primary);
> > mutex_unlock(&mgr->lock);
> >
> > if (send_remove)
> > - drm_dp_destroy_payload_step1(mgr, mst_state, payload);
> > + drm_dp_destroy_payload_step1(mgr, mst_state, new_payload);
> > else
> > drm_dbg_kms(mgr->dev, "Payload for VCPI %d not in topology, not sending remove\n",
> > - payload->vcpi);
> > + new_payload->vcpi);
> >
> > list_for_each_entry(pos, &mst_state->payloads, next) {
> > - if (pos != payload && pos->vc_start_slot > payload->vc_start_slot)
> > - pos->vc_start_slot -= payload->time_slots;
> > + if (pos != new_payload && pos->vc_start_slot > new_payload->vc_start_slot)
> > + pos->vc_start_slot -= old_payload->time_slots;
> > }
> > - payload->vc_start_slot = -1;
> > + new_payload->vc_start_slot = -1;
> >
> > mgr->payload_count--;
> > - mgr->next_start_slot -= payload->time_slots;
> > + mgr->next_start_slot -= old_payload->time_slots;
> >
> > - if (payload->delete)
> > - drm_dp_mst_put_port_malloc(payload->port);
> > + if (new_payload->delete)
> > + drm_dp_mst_put_port_malloc(new_payload->port);
> > }
> > EXPORT_SYMBOL(drm_dp_remove_payload);
> >
> > diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c b/drivers/gpu/drm/i915/display/intel_dp_mst.c
> > index f3cb12dcfe0a7..dc4e5ff1dbb31 100644
> > --- a/drivers/gpu/drm/i915/display/intel_dp_mst.c
> > +++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c
> > @@ -526,6 +526,8 @@ static void intel_mst_disable_dp(struct intel_atomic_state *state,
> > to_intel_connector(old_conn_state->connector);
> > struct drm_dp_mst_topology_state *mst_state =
> > drm_atomic_get_mst_topology_state(&state->base, &intel_dp->mst_mgr);
> > + struct drm_dp_mst_atomic_payload *payload =
> > + drm_atomic_get_mst_payload_state(mst_state, connector->port);
> > struct drm_i915_private *i915 = to_i915(connector->base.dev);
> >
> > drm_dbg_kms(&i915->drm, "active links %d\n",
> > @@ -534,7 +536,7 @@ static void intel_mst_disable_dp(struct intel_atomic_state *state,
> > intel_hdcp_disable(intel_mst->connector);
> >
> > drm_dp_remove_payload(&intel_dp->mst_mgr, mst_state,
> > - drm_atomic_get_mst_payload_state(mst_state, connector->port));
> > + payload, payload);
> >
> > intel_audio_codec_disable(encoder, old_crtc_state, old_conn_state);
> > }
> > diff --git a/drivers/gpu/drm/nouveau/dispnv50/disp.c b/drivers/gpu/drm/nouveau/dispnv50/disp.c
> > index edcb2529b4025..ed9d374147b8d 100644
> > --- a/drivers/gpu/drm/nouveau/dispnv50/disp.c
> > +++ b/drivers/gpu/drm/nouveau/dispnv50/disp.c
> > @@ -885,7 +885,7 @@ nv50_msto_prepare(struct drm_atomic_state *state,
> >
> > // TODO: Figure out if we want to do a better job of handling VCPI allocation failures here?
> > if (msto->disabled) {
> > - drm_dp_remove_payload(mgr, mst_state, payload);
> > + drm_dp_remove_payload(mgr, mst_state, payload, payload);
> >
> > nvif_outp_dp_mst_vcpi(&mstm->outp->outp, msto->head->base.index, 0, 0, 0, 0);
> > } else {
> > diff --git a/include/drm/display/drm_dp_mst_helper.h b/include/drm/display/drm_dp_mst_helper.h
> > index 41fd8352ab656..f5eb9aa152b14 100644
> > --- a/include/drm/display/drm_dp_mst_helper.h
> > +++ b/include/drm/display/drm_dp_mst_helper.h
> > @@ -841,7 +841,8 @@ int drm_dp_add_payload_part2(struct drm_dp_mst_topology_mgr *mgr,
> > struct drm_dp_mst_atomic_payload *payload);
> > void drm_dp_remove_payload(struct drm_dp_mst_topology_mgr *mgr,
> > struct drm_dp_mst_topology_state *mst_state,
> > - struct drm_dp_mst_atomic_payload *payload);
> > + const struct drm_dp_mst_atomic_payload *old_payload,
> > + struct drm_dp_mst_atomic_payload *new_payload);
> >
> > int drm_dp_check_act_status(struct drm_dp_mst_topology_mgr *mgr);
> >
>
> --
> Cheers,
> Lyude Paul (she/her)
> Software Engineer at Red Hat
>
