linux-kernel - Re: [PATCH] drm/exynos: fix vblank handling during dpms off

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Message-id: <542D2E7C.1020904@samsung.com>
Date:	Thu, 02 Oct 2014 19:52:44 +0900
From:	Inki Dae <inki.dae@...sung.com>
To:	Joonyoung Shim <jy0922.shim@...sung.com>
Cc:	Andrzej Hajda <a.hajda@...sung.com>,
	Seung-Woo Kim <sw0312.kim@...sung.com>,
	Kyungmin Park <kyungmin.park@...sung.com>,
	David Airlie <airlied@...ux.ie>,
	Kukjin Kim <kgene.kim@...sung.com>,
	dri-devel@...ts.freedesktop.org, linux-samsung-soc@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm/exynos: fix vblank handling during dpms off

On 2014년 10월 02일 17:58, Joonyoung Shim wrote:
> Hi Andrzej,
> 
> On 10/01/2014 05:14 PM, Andrzej Hajda wrote:
>> The patch disables vblanks during dpms off only if pagefilp has
>> not been finished. It also replaces drm_vblank_off with drm_crtc_vblank_put.
>> It fixes issue with page_flip ioctl not being able to acquire vblank counter.
> 
> This problem isn't related with pageflip, it just causes from
> 7ffd7a68511c710b84db3548a1997fd2625f580a commit (drm: Always reject
> drm_vblank_get() after drm_vblank_off()).
> 
> We need to use drm_vblank_on() as a counterpart to drm_vblank_off()
> after the commit .
> 
> How about below patch?

Thanks you Joonyoung and Andrzej,

drm_vblank_on/off() are legacy api so it would be better to use
drm_vblank_crtc_on/off functions instead.

And drm_vblank_crtc_off() makes sure that the latest vblank frame count
is stored and restored by drm_vblank_crtc_on() again. So my opinion is,

static void exynos_drm_crtc_dpms(struct drm_crtc *crtc, int mode)
{
	[snip]

	if (mode > DRM_MODE_DPMS_ON) {
		/* wait for the completion of page flip. */
		if (!wait_event_timeout(exynos_crtc->pending_flip_queue,
				!atomic_read(&exynos_crtc->pending_flip),
				HZ/20))
			atomic_set(&exynos_crtc->pending_flip, 0);
		drm_crtc_vblank_off(crtc);		//<- store the latest vblank frame count.
	} else {
		drm_crtc_vblank_on(crtc);		//<- restore the vblank frame count.
	}

	[snip]
}


Tested and worked well with above patch. How about it?

Thanks,
Inki Dae

> 
>>>From 6de01473746af225c688ee430123001d57d9af2a Mon Sep 17 00:00:00 2001
> From: Joonyoung Shim <jy0922.shim@...sung.com>
> Date: Thu, 2 Oct 2014 17:48:27 +0900
> Subject: [PATCH] drm/exynos: use drm_vblank_on()
> 
> We need to use drm_vblank_on() as a counterpart to drm_vblank_off()
> after the commit 7ffd7a68511c ("drm: Always reject drm_vblank_get()
> after drm_vblank_off()"). If not, drm_vblank_get() will be failed
> always after drm_vblank_off().
> 
> Signed-off-by: Joonyoung Shim <jy0922.shim@...sung.com>
> ---
>  drivers/gpu/drm/exynos/exynos_drm_crtc.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/exynos/exynos_drm_crtc.c b/drivers/gpu/drm/exynos/exynos_drm_crtc.c
> index 8e38e9f..dfa209a 100644
> --- a/drivers/gpu/drm/exynos/exynos_drm_crtc.c
> +++ b/drivers/gpu/drm/exynos/exynos_drm_crtc.c
> @@ -71,7 +71,6 @@ static void exynos_drm_crtc_dpms(struct drm_crtc *crtc, int mode)
>  				!atomic_read(&exynos_crtc->pending_flip),
>  				HZ/20))
>  			atomic_set(&exynos_crtc->pending_flip, 0);
> -		drm_vblank_off(crtc->dev, exynos_crtc->pipe);
>  	}
>  
>  	if (manager->ops->dpms)
> @@ -90,6 +89,7 @@ static void exynos_drm_crtc_commit(struct drm_crtc *crtc)
>  	struct exynos_drm_crtc *exynos_crtc = to_exynos_crtc(crtc);
>  	struct exynos_drm_manager *manager = exynos_crtc->manager;
>  
> +	drm_vblank_on(crtc->dev, exynos_crtc->pipe);
>  	exynos_drm_crtc_dpms(crtc, DRM_MODE_DPMS_ON);
>  
>  	exynos_plane_commit(crtc->primary);
> @@ -177,10 +177,12 @@ static int exynos_drm_crtc_mode_set_base(struct drm_crtc *crtc, int x, int y,
>  
>  static void exynos_drm_crtc_disable(struct drm_crtc *crtc)
>  {
> +	struct exynos_drm_crtc *exynos_crtc = to_exynos_crtc(crtc);
>  	struct drm_plane *plane;
>  	int ret;
>  
>  	exynos_drm_crtc_dpms(crtc, DRM_MODE_DPMS_OFF);
> +	drm_vblank_off(crtc->dev, exynos_crtc->pipe);
>  
>  	drm_for_each_legacy_plane(plane, &crtc->dev->mode_config.plane_list) {
>  		if (plane->crtc != crtc)
> 

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