Re: [Intel-gfx] [PATCH v2 02/17] drm/display/dp_mst: Handle old/new payload states in drm_dp_remove_payload()

From: Lyude Paul <lyude@redhat.com>
To: imre.deak@intel.com
Cc: dri-devel@lists.freedesktop.org,
	Karol Herbst <kherbst@redhat.com>,
	intel-gfx@lists.freedesktop.org, stable@vger.kernel.org,
	Ben Skeggs <bskeggs@redhat.com>, Wayne Lin <Wayne.Lin@amd.com>,
	Alex Deucher <alexander.deucher@amd.com>,
	Harry Wentland <harry.wentland@amd.com>
Subject: Re: [Intel-gfx] [PATCH v2 02/17] drm/display/dp_mst: Handle old/new payload states in drm_dp_remove_payload()
Date: Mon, 06 Feb 2023 19:42:32 -0500	[thread overview]
Message-ID: <c74b71b1d998ce6b062405508354dd1943aafa38.camel@redhat.com> (raw)
In-Reply-To: <Y9p/ZqVVpW/YMdUy@ideak-desk.fi.intel.com>

On Wed, 2023-02-01 at 17:04 +0200, Imre Deak wrote:
> 
> 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.

Ideally it'd be nice if we could have all this info in the atomic commit, but
yeah - you're not the first person to find this a bit confusing. FWIW though,
the way we store start_slot right now is intended to follow the same kind of
behavior we have with atomic CRTC commit dependencies, I think I also made it
that way so all of the state would be in a single place but there's no hard
requirement for it.

So if you guys think it'd be better design-wise to store this something else,
I've got no strong feelings either way
> 
> > For 0-2:
> > 
> > Reviewed-by: Lyude Paul <lyude@redhat.com>
> 
> Thanks.
> 
> > 
> > > 
> > > Cc: Lyude Paul <lyude@redhat.com>
> > > Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > > Cc: Ben Skeggs <bskeggs@redhat.com>
> > > Cc: Karol Herbst <kherbst@redhat.com>
> > > Cc: Harry Wentland <harry.wentland@amd.com>
> > > Cc: Alex Deucher <alexander.deucher@amd.com>
> > > Cc: Wayne Lin <Wayne.Lin@amd.com>
> > > Cc: stable@vger.kernel.org # 6.1
> > > Cc: dri-devel@lists.freedesktop.org
> > > Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > > Signed-off-by: Imre Deak <imre.deak@intel.com>
> > > ---
> > >  .../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
> > 
> 

-- 
Cheers,
 Lyude Paul (she/her)
 Software Engineer at Red Hat