[PATCH v4 2/2] drm/i915/alpm: Stop writing ALPM registers when PSR is enabled

[Kandpal, Suraj]

> -----Original Message-----
> From: Hogander, Jouni <jouni.hogander at intel.com>
> Sent: Tuesday, May 13, 2025 11:18 AM
> To: intel-gfx at lists.freedesktop.org; intel-xe at lists.freedesktop.org
> Cc: Manna, Animesh <animesh.manna at intel.com>; Kandpal, Suraj
> <suraj.kandpal at intel.com>; Hogander, Jouni <jouni.hogander at intel.com>
> Subject: [PATCH v4 2/2] drm/i915/alpm: Stop writing ALPM registers when PSR
> is enabled
> 
> Currently we are seeing these on PTL:
> 
> xe 0000:00:02.0: [drm] *ERROR* Timeout waiting for DDI BUF A to get active
> 
> These seem to be caused by writing ALPM registers while Panel Replay is
> enabled.
> 
> Fix this by writing ALPM registers only when Panel Replay is about to be
> enabled.
> 
> v4: improve comment on intel_psr_panel_replay_enable_sink call
> v3: enable/disable ALPM from PSR code
> 
> Fixes: 172757acd6f6 ("drm/i915/lobf: Add lobf enablement in post plane
> update")
> Signed-off-by: Jouni Högander <jouni.hogander at intel.com>

LGTM,
Reviewed-by: Suraj Kandpal <suraj.kandpal at intel.com>

> ---
>  drivers/gpu/drm/i915/display/intel_alpm.c |  4 ++--
> drivers/gpu/drm/i915/display/intel_psr.c  | 13 ++++++++++---
>  2 files changed, 12 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_alpm.c
> b/drivers/gpu/drm/i915/display/intel_alpm.c
> index da70a98a1292..c176bdbc19a3 100644
> --- a/drivers/gpu/drm/i915/display/intel_alpm.c
> +++ b/drivers/gpu/drm/i915/display/intel_alpm.c
> @@ -453,8 +453,8 @@ void intel_alpm_post_plane_update(struct
> intel_atomic_state *state,
>  		intel_atomic_get_old_crtc_state(state, crtc);
>  	struct intel_encoder *encoder;
> 
> -	if ((!crtc_state->has_lobf ||
> -	     crtc_state->has_lobf == old_crtc_state->has_lobf) && !crtc_state-
> >has_psr)
> +	if (crtc_state->has_psr || !crtc_state->has_lobf ||
> +	    crtc_state->has_lobf == old_crtc_state->has_lobf)
>  		return;
> 
>  	for_each_intel_encoder_mask(display->drm, encoder, diff --git
> a/drivers/gpu/drm/i915/display/intel_psr.c
> b/drivers/gpu/drm/i915/display/intel_psr.c
> index ccd66bbc72f7..430ad4ef7146 100644
> --- a/drivers/gpu/drm/i915/display/intel_psr.c
> +++ b/drivers/gpu/drm/i915/display/intel_psr.c
> @@ -800,6 +800,8 @@ static void _psr_enable_sink(struct intel_dp *intel_dp,
> static void intel_psr_enable_sink(struct intel_dp *intel_dp,
>  				  const struct intel_crtc_state *crtc_state)  {
> +	intel_alpm_enable_sink(intel_dp, crtc_state);
> +
>  	crtc_state->has_panel_replay ?
>  		_panel_replay_enable_sink(intel_dp, crtc_state) :
>  		_psr_enable_sink(intel_dp, crtc_state); @@ -1962,6 +1964,8
> @@ static void intel_psr_enable_source(struct intel_dp *intel_dp,
>  	     IS_DISPLAY_VERx100_STEP(display, 3000, STEP_A0, STEP_B0)) &&
>  	    !intel_dp->psr.panel_replay_enabled)
>  		intel_dmc_block_pkgc(display, intel_dp->psr.pipe, true);
> +
> +	intel_alpm_configure(intel_dp, crtc_state);
>  }
> 
>  static bool psr_interrupt_error_check(struct intel_dp *intel_dp) @@ -2029,8
> +2033,9 @@ static void intel_psr_enable_locked(struct intel_dp *intel_dp,
>  			    intel_dp->psr.sel_update_enabled ? "2" : "1");
> 
>  	/*
> -	 * Enabling here only for PSR. Panel Replay enable bit is already
> -	 * written at this point. See
> +	 * Enabling sink PSR/Panel Replay here only for PSR. Panel Replay
> enable
> +	 * bit is already written at this point. Sink ALPM is enabled here for
> +	 * PSR and Panel Replay. See
>  	 * intel_psr_panel_replay_enable_sink. Modifiers/options:
>  	 *  - Selective Update
>  	 *  - Region Early Transport
> @@ -2172,6 +2177,9 @@ static void intel_psr_disable_locked(struct intel_dp
> *intel_dp)
>  	if (intel_dp_is_edp(intel_dp))
> 
> 	intel_snps_phy_update_psr_power_state(&dp_to_dig_port(intel_dp)-
> >base, false);
> 
> +	if (intel_dp->psr.panel_replay_enabled && intel_dp_is_edp(intel_dp))
> +		intel_alpm_disable(intel_dp);
> +
>  	/* Disable PSR on Sink */
>  	if (!intel_dp->psr.panel_replay_enabled) {
>  		drm_dp_dpcd_writeb(&intel_dp->aux, DP_PSR_EN_CFG, 0);
> @@ -3498,7 +3506,6 @@ static void psr_alpm_check(struct intel_dp *intel_dp)
>  	if (intel_alpm_get_error(intel_dp)) {
>  		intel_psr_disable_locked(intel_dp);
>  		psr->sink_not_reliable = true;
> -		intel_alpm_disable(intel_dp);
>  	}
>  }
> 
> --
> 2.43.0