linux-kernel - Re: [PATCH RESEND] drm/self_refresh: Don't trigger the entry timer for self refresh work if CRTC state is inactive

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Date:   Mon, 07 Mar 2022 10:33:41 +0800
From:   Liu Ying <victor.liu@....com>
To:     dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Cc:     linux-imx@....com, Rob Clark <robdclark@...omium.org>,
        Sean Paul <seanpaul@...omium.org>,
        Zain Wang <wzz@...k-chips.com>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>
Subject: Re: [PATCH RESEND] drm/self_refresh: Don't trigger the entry timer
 for self refresh work if CRTC state is inactive

On Mon, 2022-02-07 at 13:46 +0800, Liu Ying wrote:
> If the CRTC state is already inactive, it doesn't make sense to trigger
> the entry timer for self refresh work to make the display enter self
> refresh mode, because the disabled CRTC hints that either the entire
> display pipeline is disabled or the previous atomic commit is triggered
> by the self refresh work(the CRTC is disabled, while the relevant encoder
> and bridges could be disabled or not depending on the drivers).
> 
> Cc: Rob Clark <robdclark@...omium.org>
> Cc: Sean Paul <seanpaul@...omium.org>
> Cc: Zain Wang <wzz@...k-chips.com>
> Cc: Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>
> Cc: Maxime Ripard <mripard@...nel.org>
> Cc: Thomas Zimmermann <tzimmermann@...e.de>
> Cc: David Airlie <airlied@...ux.ie>
> Cc: Daniel Vetter <daniel@...ll.ch>
> Signed-off-by: Liu Ying <victor.liu@....com>

Gentle ping...

Thanks,
Liu Ying

> ---
>  drivers/gpu/drm/drm_self_refresh_helper.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_self_refresh_helper.c b/drivers/gpu/drm/drm_self_refresh_helper.c
> index dd33fec5aabd..e76eb3cd22c7 100644
> --- a/drivers/gpu/drm/drm_self_refresh_helper.c
> +++ b/drivers/gpu/drm/drm_self_refresh_helper.c
> @@ -204,8 +204,12 @@ void drm_self_refresh_helper_alter_state(struct drm_atomic_state *state)
>  		struct drm_self_refresh_data *sr_data;
>  		unsigned int delay;
>  
> -		/* Don't trigger the entry timer when we're already in SR */
> -		if (crtc_state->self_refresh_active)
> +		/*
> +		 * Don't trigger the entry timer when we're already inactive.
> +		 * Note that the inactive state hints that either we're already
> +		 * in SR or the entire display pipeline is already disabled.
> +		 */
> +		if (!crtc_state->active)
>  			continue;
>  
>  		sr_data = crtc->self_refresh_data;