Re: [PATCH v6 11/12] drm/i915/display: Ensure we have "Frame Change" event in DSB commit

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Mon, Jan 27, 2025 at 12:28:45PM +0200, Jouni Högander wrote:
> We may have commit which doesn't have any non-arming plane register
> writes. In that case there aren't "Frame Change" event before DSB vblank
> evasion which hangs as PIPEDSL register is reading as 0 when PSR state is
> SRDENT(PSR1) or DEEP_SLEEP(PSR2). Handle this by ensuring "Frame Change"
> event at the begin of DSB commit if using PSR/PR.
> 
> v2: use intel_psr_trigger_frame_change_event
> 
> Signed-off-by: Jouni Högander <jouni.hogander@intel.com>

Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

> ---
>  drivers/gpu/drm/i915/display/intel_display.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
> index 5db2af86d0c8a..67041d76763fe 100644
> --- a/drivers/gpu/drm/i915/display/intel_display.c
> +++ b/drivers/gpu/drm/i915/display/intel_display.c
> @@ -7725,6 +7725,14 @@ static void intel_atomic_dsb_finish(struct intel_atomic_state *state,
>  		intel_crtc_planes_update_noarm(new_crtc_state->dsb_commit,
>  					       state, crtc);
>  
> +		/*
> +		 * Ensure we have "Frame Change" event when PSR state is
> +		 * SRDENT(PSR1) or DEEP_SLEEP(PSR2). Otherwise DSB vblank
> +		 * evasion hangs as PIPEDSL is reading as 0.
> +		 */
> +		intel_psr_trigger_frame_change_event(state, new_crtc_state->dsb_commit,
> +						     crtc);
> +
>  		intel_dsb_vblank_evade(state, new_crtc_state->dsb_commit);
>  
>  		if (intel_crtc_needs_color_update(new_crtc_state))
> -- 
> 2.43.0

-- 
Ville Syrjälä
Intel