[PATCH v2 1/1] drm/i915/display: Add no_psr_reason to PSR debugfs

[Kahola, Mika]

> -----Original Message-----
> From: Intel-xe <intel-xe-bounces at lists.freedesktop.org> On Behalf Of Michal Grzelak
> Sent: Thursday, 5 June 2025 12.13
> To: intel-gfx at lists.freedesktop.org; intel-xe at lists.freedesktop.org
> Cc: Grzelak, Michal <michal.grzelak at intel.com>
> Subject: [PATCH v2 1/1] drm/i915/display: Add no_psr_reason to PSR debugfs
> 
> There is no reason in debugfs why PSR has been disabled. Add no_psr_reason field into struct intel_psr. Write the reason, e.g. PSR
> setup timing not met, into proper PSR debugfs file.
> Clean it when PSR is activated.
> 
> Signed-off-by: Michał Grzelak <michal.grzelak at intel.com>
> ---
>  .../drm/i915/display/intel_display_types.h    |  2 +
>  drivers/gpu/drm/i915/display/intel_psr.c      | 38 ++++++++++++-------
>  2 files changed, 26 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h b/drivers/gpu/drm/i915/display/intel_display_types.h
> index 7415564d058a..7d598357a702 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_types.h
> +++ b/drivers/gpu/drm/i915/display/intel_display_types.h
> @@ -1653,6 +1653,8 @@ struct intel_psr {
>  	bool link_ok;
> 
>  	u8 active_non_psr_pipes;
> +
> +	const char *no_psr_reason;
>  };
> 
>  struct intel_dp {
> diff --git a/drivers/gpu/drm/i915/display/intel_psr.c b/drivers/gpu/drm/i915/display/intel_psr.c
> index ccd66bbc72f7..2c8af2a10ee1 100644
> --- a/drivers/gpu/drm/i915/display/intel_psr.c
> +++ b/drivers/gpu/drm/i915/display/intel_psr.c
> @@ -1577,6 +1577,7 @@ static bool _psr_compute_config(struct intel_dp *intel_dp,
>  	if (entry_setup_frames >= 0) {
>  		intel_dp->psr.entry_setup_frames = entry_setup_frames;
>  	} else {
> +		intel_dp->psr.no_psr_reason = "PSR setup timing not met";
>  		drm_dbg_kms(display->drm,
>  			    "PSR condition failed: PSR setup timing not met\n");
>  		return false;
> @@ -1812,6 +1813,7 @@ static void intel_psr_activate(struct intel_dp *intel_dp)
>  		hsw_activate_psr1(intel_dp);
> 
>  	intel_dp->psr.active = true;
> +	intel_dp->psr.no_psr_reason = NULL;
>  }
> 
>  /*
> @@ -2904,13 +2906,21 @@ void intel_psr_pre_plane_update(struct intel_atomic_state *state,
>  			 * - Region Early Transport changing
>  			 * - Display WA #1136: skl, bxt
>  			 */
> -			if (intel_crtc_needs_modeset(new_crtc_state) ||
> -			    !new_crtc_state->has_psr ||
> -			    !new_crtc_state->active_planes ||
> -			    new_crtc_state->has_sel_update != psr->sel_update_enabled ||
> -			    new_crtc_state->enable_psr2_su_region_et != psr->su_region_et_enabled ||
> -			    new_crtc_state->has_panel_replay != psr->panel_replay_enabled ||
> -			    (DISPLAY_VER(display) < 11 && new_crtc_state->wm_level_disabled))
> +			if (intel_crtc_needs_modeset(new_crtc_state))
> +				psr->no_psr_reason = "New state needs modeset";
Phrasing these statements are always matter of a opinion but I would rephrase this as following

psr->no_psr_reason = "CRTC needs modeset" 

as crtc state is simply a state of the crtc and crtc is the one that needs mode setting.

> +			if (!new_crtc_state->has_psr)
> +		                psr->no_psr_reason = "PSR disabled in new state";
These reasons are listed in the comment of this section of code. However, since has_psr is not true, the PSR is disabled whatever reason (due to lack of planes etc.) I would simply rephrase this as

psr->no_psr_reason = "PSR disabled"

> +			if (!new_crtc_state->active_planes)
> +		                psr->no_psr_reason = "All planes will go inactive";
Maybe just

psr->no_psr_reason = "All planes inactive"

> +			if (new_crtc_state->has_sel_update != psr->sel_update_enabled)
> +				psr->no_psr_reason = "Changing between PSR versions";
> +			if (new_crtc_state->enable_psr2_su_region_et != psr->su_region_et_enabled)
> +		                psr->no_psr_reason = "Region Early Transport changing";
Since reasons above and below this starts with "Changing" and the comparison is similar, maybe we could rephrase this similarly i.e.

psr->no_psr_reason = "Changing Region Early Transport"

> +			if (new_crtc_state->has_panel_replay != psr->panel_replay_enabled)
> +				psr->no_psr_reason = "Changing Panel Replay mode";
> +			if (DISPLAY_VER(display) < 11 && new_crtc_state->wm_level_disabled)
> +			        psr->no_psr_reason = "Bspec #21664 Display WA #1136: skl, bxt";
> +			if (psr->no_psr_reason)
>  				intel_psr_disable_locked(intel_dp);
>  			else if (new_crtc_state->wm_level_disabled)
>  				/* Wa_14015648006 */
> @@ -3918,12 +3928,7 @@ static void intel_psr_print_mode(struct intel_dp *intel_dp,
>  				 struct seq_file *m)
>  {
>  	struct intel_psr *psr = &intel_dp->psr;
> -	const char *status, *mode, *region_et;
> -
> -	if (psr->enabled)
> -		status = " enabled";
> -	else
> -		status = "disabled";
> +	const char *mode, *region_et;
> 
>  	if (psr->panel_replay_enabled && psr->sel_update_enabled)
>  		mode = "Panel Replay Selective Update"; @@ -3941,7 +3946,12 @@ static void intel_psr_print_mode(struct
> intel_dp *intel_dp,
>  	else
>  		region_et = "";
> 
> -	seq_printf(m, "PSR mode: %s%s%s\n", mode, status, region_et);
> +	if (psr->enabled) {
> +		seq_puts(m, "PSR enabled\n");
> +		seq_printf(m, "PSR mode: %s%s\n", mode, region_et);
> +	} else {
> +		seq_printf(m, "PSR disabled: %s\n", psr->no_psr_reason);
> +	}
>  }
> 
>  static int intel_psr_status(struct seq_file *m, struct intel_dp *intel_dp)
> --
> 2.45.2

Otherwise, the patch looks good.