Re: [PATCH] drm/i915/display: Only fail fastset on PSR2

[Hogander, Jouni]

On Tue, 2023-10-31 at 23:21 +0000, Paz Zcharya wrote:
> Currently, i915 fails fastset if both the sink and the source support
> any version of PSR and regardless of the configuration setting of the
> driver (i.e., i915.enable_psr kernel argument). However, the
> implementation of PSR1 enable sequence is already seamless
> and works smoothly with fastset. Accordingly, do not fail fastset
> if PSR2 is not enabled.

Thank you for the patch. Check similar patch I sent some time ago to
trybot:

https://patchwork.freedesktop.org/series/125392/

If we want to temporarily do this only for psr1 I think you could check
what I've done in drivers/gpu/drm/i915/display/intel_display.c in my
patch and modify your patch accordingly. Otherwise e.g. our IGT
testcases which are toggling PSR enable/disable/psr1/psr2 are to my
understanding performing full modeset and possible issues are not
revealed.

After modifying drivers/gpu/drm/i915/display/intel_display.c you can
also verify it is really seamless and smooth by toggling different PSR
states via /sys/kernel/debug/dri/0/i915_edp_psr_debug. That interface
is performing atomic commit when PSR mode is changed.

BR,

Jouni Högander
> 
> Signed-off-by: Paz Zcharya <pazz@xxxxxxxxxx>
> ---
> 
>  drivers/gpu/drm/i915/display/intel_dp.c  | 4 ++--
>  drivers/gpu/drm/i915/display/intel_psr.c | 2 +-
>  drivers/gpu/drm/i915/display/intel_psr.h | 1 +
>  3 files changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c
> b/drivers/gpu/drm/i915/display/intel_dp.c
> index e0e4cb529284..a1af96e31518 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -2584,8 +2584,8 @@ bool intel_dp_initial_fastset_check(struct
> intel_encoder *encoder,
>                 fastset = false;
>         }
>  
> -       if (CAN_PSR(intel_dp)) {
> -               drm_dbg_kms(&i915->drm, "[ENCODER:%d:%s] Forcing full
> modeset to compute PSR state\n",
> +       if (CAN_PSR(intel_dp) && psr2_global_enabled(intel_dp)) {
> +               drm_dbg_kms(&i915->drm, "[ENCODER:%d:%s] Forcing full
> modeset due to PSR2\n",
>                             encoder->base.base.id, encoder-
> >base.name);
>                 crtc_state->uapi.mode_changed = true;
>                 fastset = false;
> diff --git a/drivers/gpu/drm/i915/display/intel_psr.c
> b/drivers/gpu/drm/i915/display/intel_psr.c
> index 97d5eef10130..388bc3246db9 100644
> --- a/drivers/gpu/drm/i915/display/intel_psr.c
> +++ b/drivers/gpu/drm/i915/display/intel_psr.c
> @@ -187,7 +187,7 @@ static bool psr_global_enabled(struct intel_dp
> *intel_dp)
>         }
>  }
>  
> -static bool psr2_global_enabled(struct intel_dp *intel_dp)
> +bool psr2_global_enabled(struct intel_dp *intel_dp)
>  {
>         struct drm_i915_private *i915 = dp_to_i915(intel_dp);
>  
> diff --git a/drivers/gpu/drm/i915/display/intel_psr.h
> b/drivers/gpu/drm/i915/display/intel_psr.h
> index 0b95e8aa615f..6f3c36389cd3 100644
> --- a/drivers/gpu/drm/i915/display/intel_psr.h
> +++ b/drivers/gpu/drm/i915/display/intel_psr.h
> @@ -21,6 +21,7 @@ struct intel_encoder;
>  struct intel_plane;
>  struct intel_plane_state;
>  
> +bool psr2_global_enabled(struct intel_dp *intel_dp);
>  void intel_psr_init_dpcd(struct intel_dp *intel_dp);
>  void intel_psr_pre_plane_update(struct intel_atomic_state *state,
>                                 struct intel_crtc *crtc);