[Intel-gfx] [PATCH] drm/i915/display: refine eDP power off sequence

[Ville Syrjälä]

On Wed, Aug 31, 2022 at 06:37:24PM +0800, Lee Shawn C wrote:
> The current eDP disable sequence like this.
> 
> disable plane > disable backlight (include T9, the delay
> from backlight disable to end of valid video data) >
> disalbe transcoder/pipe > disable eDP power
> 
> Found abnormal pixel output after plane off sometimes.
> It did not cause any issue but impact user experience.
> So we modify the eDP disable flow to turn backlight off
> earlier to avoid abnormal display.

NAK. Planes can be disable at any time by userspace.
We need to find out what is causing the glitch.

> 
> disable backlight > disable plane > disalbe transcoder/pipe
> > disable eDP power
> 
> Cc: Shankar Uma <uma.shankar at intel.com>
> Cc: Jani Nikula <jani.nikula at linux.intel.com>
> Signed-off-by: Lee Shawn C <shawn.c.lee at intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_display.c | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
> index 72e2091d9fcb..d08927036350 100644
> --- a/drivers/gpu/drm/i915/display/intel_display.c
> +++ b/drivers/gpu/drm/i915/display/intel_display.c
> @@ -2045,10 +2045,8 @@ static void hsw_crtc_disable(struct intel_atomic_state *state,
>  	 * FIXME collapse everything to one hook.
>  	 * Need care with mst->ddi interactions.
>  	 */
> -	if (!intel_crtc_is_bigjoiner_slave(old_crtc_state)) {
> -		intel_encoders_disable(state, crtc);
> +	if (!intel_crtc_is_bigjoiner_slave(old_crtc_state))
>  		intel_encoders_post_disable(state, crtc);
> -	}
>  }
>  
>  static void i9xx_pfit_enable(const struct intel_crtc_state *crtc_state)
> @@ -7224,6 +7222,10 @@ static void intel_commit_modeset_disables(struct intel_atomic_state *state)
>  			continue;
>  
>  		intel_pre_plane_update(state, crtc);
> +
> +		if (!intel_crtc_is_bigjoiner_slave(old_crtc_state))
> +			intel_encoders_disable(state, crtc);
> +
>  		intel_crtc_disable_planes(state, crtc);
>  	}
>  
> -- 
> 2.31.1

-- 
Ville Syrjälä
Intel