Re: [PATCH 5/8] drm/i915/psr: Clear pr_dpcd as well on disconnect

["Hogander, Jouni" <jouni.hogander@intel.com>]

On Wed, 2025-12-03 at 16:37 +0200, Imre Deak wrote:
> On Mon, Dec 01, 2025 at 01:23:41PM +0200, Jouni Hogander wrote:
> > On Mon, 2025-12-01 at 12:53 +0200, Imre Deak wrote:
> > > On Fri, Nov 21, 2025 at 01:16:52PM +0200, Jouni Högander wrote:
> > > > Currently we are leaving pr_dpcd containing Panel Replay
> > > > capability
> > > > DPCD registers as it is on disconnect. Clear it as well on
> > > > disconnect.
> > > > 
> > > > Signed-off-by: Jouni Högander <jouni.hogander@intel.com>
> > > > ---
> > > >  drivers/gpu/drm/i915/display/intel_dp.c | 1 +
> > > >  1 file changed, 1 insertion(+)
> > > > 
> > > > diff --git a/drivers/gpu/drm/i915/display/intel_dp.c
> > > > b/drivers/gpu/drm/i915/display/intel_dp.c
> > > > index 62808cd35f5f2..7195c408d93ab 100644
> > > > --- a/drivers/gpu/drm/i915/display/intel_dp.c
> > > > +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> > > > @@ -6050,6 +6050,7 @@ intel_dp_detect(struct drm_connector
> > > > *_connector,
> > > >  	if (status == connector_status_disconnected) {
> > > >  		intel_dp_test_reset(intel_dp);
> > > >  		memset(connector->dp.dsc_dpcd, 0,
> > > > sizeof(connector->dp.dsc_dpcd));
> > > > +		memset(connector->dp.pr_dpcd, 0,
> > > > sizeof(connector->dp.pr_dpcd));
> > > 
> > > What about psr_dpcd?
> > 
> > PSR is only for eDP and can't be disconnected.
> 
> Ok. Panel Replay used on non-eDP has also Selective Update for
> instance,
> but that has separate PR specific capability registers. The same is
> true
> I presume for any other functionality that could be used both on PSR2
> and PR.
> 
> It's still a bit strange that intel_dp_detect() ->
> intel_psr_init_dpcd()
> -> _psr_init_dpcd() reads psr_dpcd (aka dp.psr_caps.dpcd after your
> patch) for non-eDP as well. Even though the values should not be used
> anywhere based on the above, I'd still avoid explicitly reading them
> out
> for non-eDP (only as a follow-up imo, no need to change this now).

Ok, I will take care of that.

Another thing I have been recently wondering is the eDP/DP version.
Generally speaking: should I check eDP/DP version before checking the
feature of some specific version. I have now seen couple of cases where
panel is stating Panel Replay support, but still saying it's eDP
version 1.4. and Panel Replay is non-functional.(Related patch in
trybot: https://patchwork.freedesktop.org/series/157760/)

BR,

Jouni Högander

> 
> > > All these resetting of the caps cause a problem if the connector
> > > needs to be modeset after the sink is disconnected (since then
> > > the
> > > state computation for the connector will fail seeing these caps
> > > being reset). Instead the caps should be kept intact here,
> > > resetting/reiniting them only when a new sink is connected. Since
> > > this is a pre-existing issue, could you add for now a
> > > corrsponding
> > > FIXME: comment in this patch?
> > 
> > Thank you for pointing this out. I will add the FIXME.
> > 
> > BR,
> > 
> > Jouni Högander
> > 
> > > 
> > > >  		intel_dp->psr.sink_panel_replay_support =
> > > > false;
> > > >  		intel_dp->psr.sink_panel_replay_su_support =
> > > > false;
> > > >  		intel_dp->psr.sink_panel_replay_dsc_support =
> > > > -- 
> > > > 2.43.0