On Wed, 2017-01-04 at 10:33 +0100, Daniel Vetter wrote:
> On Tue, Jan 03, 2017 at 01:01:49PM -0800, Dhinakaran Pandiyan wrote:
> > Link bandwidth is shared between multiple display streams in DP MST
> > configurations. The DP MST topology manager structure maintains the shared
> > link bandwidth for a primary link directly connected to the GPU. For atomic
> > modesetting drivers, checking if there is sufficient link bandwidth for a
> > mode needs to be done during the atomic_check phase to avoid failed
> > modesets. Let's encsapsulate the available link bw information in a state
> > structure so that bw can be allocated and released atomically for each of
> > the ports sharing the primary link.
> >
> > Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@xxxxxxxxx>
>
> Overall issue with the patch is that dp helpers now have 2 places where
> available_slots is stored: One for atomic drivers in ->state, and the
> legacy one. I think it'd be good to rework the legacy codepaths (i.e.
> drm_dp_find_vcpi_slots) to use mgr->state->avail_slots, and remove
> mgr->avail_slots entirely.
PATCH 2/6 does that. mgr->avail_slots is not updated in the legacy code
path, so the check turns out to be against mgr->total_slots. So, I did
just that, albeit explicitly.
-DK
>
> Another design concern below, but in principle this looks like what we
> need.
> -Daniel
>
>
> > ---
> > drivers/gpu/drm/drm_atomic.c | 66 +++++++++++++++++++++++++++++++++++
> > drivers/gpu/drm/drm_atomic_helper.c | 10 ++++++
> > drivers/gpu/drm/drm_dp_mst_topology.c | 10 ++++++
> > include/drm/drm_atomic.h | 13 +++++++
> > include/drm/drm_dp_mst_helper.h | 13 +++++++
> > 5 files changed, 112 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c
> > index 681d5f9..b8e2cea 100644
> > --- a/drivers/gpu/drm/drm_atomic.c
> > +++ b/drivers/gpu/drm/drm_atomic.c
> > @@ -31,6 +31,7 @@
> > #include <drm/drm_mode.h>
> > #include <drm/drm_plane_helper.h>
> > #include <drm/drm_print.h>
> > +#include <drm/drm_dp_mst_helper.h>
> > #include <linux/sync_file.h>
> >
> > #include "drm_crtc_internal.h"
> > @@ -62,6 +63,7 @@ void drm_atomic_state_default_release(struct drm_atomic_state *state)
> > kfree(state->connectors);
> > kfree(state->crtcs);
> > kfree(state->planes);
> > + kfree(state->dp_mst_topologies);
> > }
> > EXPORT_SYMBOL(drm_atomic_state_default_release);
> >
> > @@ -189,6 +191,18 @@ void drm_atomic_state_default_clear(struct drm_atomic_state *state)
> > state->planes[i].ptr = NULL;
> > state->planes[i].state = NULL;
> > }
> > +
> > + for (i = 0; i < state->num_mst_topologies; i++) {
> > + struct drm_dp_mst_topology_mgr *mgr = state->dp_mst_topologies[i].ptr;
> > +
> > + if (!mgr)
> > + continue;
> > +
> > + kfree(state->dp_mst_topologies[i].state);
> > + state->dp_mst_topologies[i].ptr = NULL;
> > + state->dp_mst_topologies[i].state = NULL;
> > + }
> > +
> > }
> > EXPORT_SYMBOL(drm_atomic_state_default_clear);
> >
> > @@ -981,6 +995,58 @@ static void drm_atomic_plane_print_state(struct drm_printer *p,
> > plane->funcs->atomic_print_state(p, state);
> > }
> >
> > +struct drm_dp_mst_topology_state *drm_atomic_get_mst_topology_state(struct drm_atomic_state *state,
> > + struct drm_dp_mst_topology_mgr *mgr)
> > +{
> > +
> > + int ret, i;
> > + size_t new_size;
> > + struct __drm_dp_mst_topology_state *new_arr;
> > + struct drm_dp_mst_topology_state *new_mst_state;
> > + int num_topologies;
> > + struct drm_mode_config *config = &mgr->dev->mode_config;
> > +
> > + WARN_ON(!state->acquire_ctx);
> > +
> > + ret = drm_modeset_lock(&config->connection_mutex, state->acquire_ctx);
> > + if (ret)
> > + return ERR_PTR(ret);
> > +
> > + for (i = 0; i < state->num_mst_topologies; i++) {
> > + if (mgr == state->dp_mst_topologies[i].ptr &&
> > + state->dp_mst_topologies[i].state) {
> > + return state->dp_mst_topologies[i].state;
> > + }
> > + }
> > +
> > + num_topologies = state->num_mst_topologies + 1;
> > + new_size = sizeof(*state->dp_mst_topologies) * num_topologies;
> > + new_arr = krealloc(state->dp_mst_topologies, new_size, GFP_KERNEL);
> > + if (!new_arr)
> > + return ERR_PTR(-ENOMEM);
> > +
> > + state->dp_mst_topologies = new_arr;
> > + memset(&state->dp_mst_topologies[state->num_mst_topologies], 0,
> > + sizeof(*state->dp_mst_topologies));
> > +
> > + new_mst_state = kmalloc(sizeof(*mgr->state), GFP_KERNEL);
> > + if (!new_mst_state)
> > + return ERR_PTR(-ENOMEM);
> > +
> > + new_mst_state->avail_slots = mgr->state->avail_slots;
> > + state->dp_mst_topologies[state->num_mst_topologies].state = new_mst_state;
> > + state->dp_mst_topologies[state->num_mst_topologies].ptr = mgr;
> > + state->num_mst_topologies = num_topologies;
> > + new_mst_state->mgr = mgr;
> > + mgr->state->state = state;
> > +
> > + DRM_DEBUG_ATOMIC("Added [MST Topology w/ base connector:%d] %p state to %p\n",
> > + mgr->conn_base_id, new_mst_state, state);
> > +
> > + return new_mst_state;
> > +}
> > +EXPORT_SYMBOL(drm_atomic_get_mst_topology_state);
> > +
> > /**
> > * drm_atomic_get_connector_state - get connector state
> > * @state: global atomic state object
> > diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
> > index 5e52244..1cd38b7 100644
> > --- a/drivers/gpu/drm/drm_atomic_helper.c
> > +++ b/drivers/gpu/drm/drm_atomic_helper.c
> > @@ -30,6 +30,7 @@
> > #include <drm/drm_plane_helper.h>
> > #include <drm/drm_crtc_helper.h>
> > #include <drm/drm_atomic_helper.h>
> > +#include <drm/drm_dp_mst_helper.h>
> > #include <linux/dma-fence.h>
> >
> > #include "drm_crtc_internal.h"
> > @@ -1992,6 +1993,15 @@ void drm_atomic_helper_swap_state(struct drm_atomic_state *state,
> > connector->state->state = NULL;
> > }
> >
> > + for (i = 0; i < state->num_mst_topologies; i++) {
> > + struct drm_dp_mst_topology_mgr *mgr;
> > +
> > + mgr = state->dp_mst_topologies[i].ptr;
> > + mgr->state->state = state;
> > + swap(state->dp_mst_topologies[i].state, mgr->state);
> > + mgr->state->state = NULL;
> > + }
>
> I'm not sure we want to tie the dp mst helpers that closely with the
> atomic machinery, otoh it makes things a lot easier. My concern is that
> drm_atomic_state is a core structure, whereas the dp_mst stuff is a
> helper, which means we have a control inversion here compared to the
> normal pattern.
>
> > +
> > for_each_crtc_in_state(state, crtc, crtc_state, i) {
> > crtc->state->state = state;
> > swap(state->crtcs[i].state, crtc->state);
> > diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
> > index d42a6c0..1be19e1 100644
> > --- a/drivers/gpu/drm/drm_dp_mst_topology.c
> > +++ b/drivers/gpu/drm/drm_dp_mst_topology.c
> > @@ -2042,6 +2042,9 @@ int drm_dp_mst_topology_mgr_set_mst(struct drm_dp_mst_topology_mgr *mgr, bool ms
> > goto out_unlock;
> > }
> >
> > + /* max. time slots - one slot for MTP header */
> > + mgr->state->avail_slots = 63;
> > +
> > /* add initial branch device at LCT 1 */
> > mstb = drm_dp_add_mst_branch_device(1, NULL);
> > if (mstb == NULL) {
> > @@ -2973,6 +2976,11 @@ int drm_dp_mst_topology_mgr_init(struct drm_dp_mst_topology_mgr *mgr,
> > mgr->proposed_vcpis = kcalloc(max_payloads, sizeof(struct drm_dp_vcpi *), GFP_KERNEL);
> > if (!mgr->proposed_vcpis)
> > return -ENOMEM;
> > + mgr->state = kzalloc(sizeof(*mgr->state), GFP_KERNEL);
> > + if (!mgr->state)
> > + return -ENOMEM;
> > + mgr->state->mgr = mgr;
> > +
> > set_bit(0, &mgr->payload_mask);
> > if (test_calc_pbn_mode() < 0)
> > DRM_ERROR("MST PBN self-test failed\n");
> > @@ -2995,6 +3003,8 @@ void drm_dp_mst_topology_mgr_destroy(struct drm_dp_mst_topology_mgr *mgr)
> > kfree(mgr->proposed_vcpis);
> > mgr->proposed_vcpis = NULL;
> > mutex_unlock(&mgr->payload_lock);
> > + kfree(mgr->state);
> > + mgr->state = NULL;
> > mgr->dev = NULL;
> > mgr->aux = NULL;
> > }
> > diff --git a/include/drm/drm_atomic.h b/include/drm/drm_atomic.h
> > index fd2d971..7ac5ed6 100644
> > --- a/include/drm/drm_atomic.h
> > +++ b/include/drm/drm_atomic.h
> > @@ -153,6 +153,11 @@ struct __drm_connnectors_state {
> > struct drm_connector_state *state;
> > };
> >
> > +struct __drm_dp_mst_topology_state {
> > + struct drm_dp_mst_topology_mgr *ptr;
> > + struct drm_dp_mst_topology_state *state;
>
> One way to fix that control inversion I mentioned above is to use void*
> pionters here, and then have callbacks for atomic_destroy and swap_state
> on top. A bit more shuffling, but we could then use that for other driver
> private objects.
>
> Other option is to stuff it into intel_atomic_state.
>
> > +};
> > +
> > /**
> > * struct drm_atomic_state - the global state object for atomic updates
> > * @ref: count of all references to this state (will not be freed until zero)
> > @@ -164,6 +169,8 @@ struct __drm_connnectors_state {
> > * @crtcs: pointer to array of CRTC pointers
> > * @num_connector: size of the @connectors and @connector_states arrays
> > * @connectors: pointer to array of structures with per-connector data
> > + * @num_mst_topologies: size of the @dp_mst_topologies array
> > + * @dp_mst_topologies: pointer to array of structures with per-MST topology manager data
> > * @acquire_ctx: acquire context for this atomic modeset state update
> > */
> > struct drm_atomic_state {
> > @@ -177,6 +184,8 @@ struct drm_atomic_state {
> > struct __drm_crtcs_state *crtcs;
> > int num_connector;
> > struct __drm_connnectors_state *connectors;
> > + int num_mst_topologies;
> > + struct __drm_dp_mst_topology_state *dp_mst_topologies;
> >
> > struct drm_modeset_acquire_ctx *acquire_ctx;
> >
> > @@ -250,6 +259,10 @@ int drm_atomic_connector_set_property(struct drm_connector *connector,
> > struct drm_connector_state *state, struct drm_property *property,
> > uint64_t val);
> >
> > +struct drm_dp_mst_topology_state * __must_check
> > +drm_atomic_get_mst_topology_state(struct drm_atomic_state *state,
> > + struct drm_dp_mst_topology_mgr *mgr);
> > +
> > /**
> > * drm_atomic_get_existing_crtc_state - get crtc state, if it exists
> > * @state: global atomic state object
> > diff --git a/include/drm/drm_dp_mst_helper.h b/include/drm/drm_dp_mst_helper.h
> > index 98d3c73..0a9bf20 100644
> > --- a/include/drm/drm_dp_mst_helper.h
> > +++ b/include/drm/drm_dp_mst_helper.h
> > @@ -403,6 +403,12 @@ struct drm_dp_payload {
> > int vcpi;
> > };
> >
> > +struct drm_dp_mst_topology_state {
> > + int avail_slots;
> > + struct drm_atomic_state *state;
> > + struct drm_dp_mst_topology_mgr *mgr;
> > +};
> > +
> > /**
> > * struct drm_dp_mst_topology_mgr - DisplayPort MST manager
> > *
> > @@ -481,6 +487,11 @@ struct drm_dp_mst_topology_mgr {
> > int pbn_div;
> >
> > /**
> > + * @state: MST topology manager state for atomic modesetting drivers
> > + */
> > + struct drm_dp_mst_topology_state *state;
> > +
> > + /**
> > * @qlock: protects @tx_msg_downq, the tx_slots in struct
> > * &drm_dp_mst_branch and txmsg->state once they are queued
> > */
> > @@ -596,4 +607,6 @@ void drm_dp_mst_dump_topology(struct seq_file *m,
> >
> > void drm_dp_mst_topology_mgr_suspend(struct drm_dp_mst_topology_mgr *mgr);
> > int drm_dp_mst_topology_mgr_resume(struct drm_dp_mst_topology_mgr *mgr);
> > +struct drm_dp_mst_topology_state *drm_atomic_get_mst_topology_state(struct drm_atomic_state *state,
> > + struct drm_dp_mst_topology_mgr *mgr);
> > #endif
> > --
> > 2.7.4
> >
>
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