linux-kernel - Re: [PATCH 1/2] drm/gma500: Add missing call to allow enabling vblank on psb/cdv

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Date:   Thu, 7 Nov 2019 15:17:44 +0100
From:   Paul Kocialkowski <paul.kocialkowski@...tlin.com>
To:     Patrik Jakobsson <patrik.r.jakobsson@...il.com>
Cc:     dri-devel <dri-devel@...ts.freedesktop.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        James Hilliard <james.hilliard1@...il.com>,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>
Subject: Re: [PATCH 1/2] drm/gma500: Add missing call to allow enabling
 vblank on psb/cdv

Hi,

On Wed 06 Nov 19, 16:23, Patrik Jakobsson wrote:
> On Wed, Nov 6, 2019 at 10:44 AM Paul Kocialkowski
> <paul.kocialkowski@...tlin.com> wrote:
> >
> > This adds a missing call to drm_crtc_vblank_on to the common DPMS helper
> > (used by poulsbo and cedartrail), which is called in the CRTC enable path.
> >
> > With that call, it becomes possible to enable vblank when needed.
> > It is already balanced by a drm_crtc_vblank_off call in the helper.
> >
> > Other platforms (oaktrail and medfield) use a dedicated DPMS helper that
> > does not have the proper vblank on/off hooks. They are not added in this
> > commit due to lack of hardware to test it with.
> >
> > Signed-off-by: Paul Kocialkowski <paul.kocialkowski@...tlin.com>
> 
> Don't think we ever found a need for having vblanks enabled... until
> now. I'll have a look if something can be done for Oaktrail since I
> have hw.

Neat, thanks!

IIRC the DPMS paths that don't use gma_crtc_dpms also lack the proper
drm_crtc_vblank_on/off calls so that's probably something to start with :)

Thanks for the review on these patches. I may have more fixes coming up.

Cheers,

Paul

> Reviewed-by: Patrik Jakobsson <patrik.r.jakobsson@...il.com>
> 
> > ---
> >  drivers/gpu/drm/gma500/gma_display.c | 2 ++
> >  1 file changed, 2 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/gma500/gma_display.c b/drivers/gpu/drm/gma500/gma_display.c
> > index e20ccb5d10fd..bc07ae2a9a1d 100644
> > --- a/drivers/gpu/drm/gma500/gma_display.c
> > +++ b/drivers/gpu/drm/gma500/gma_display.c
> > @@ -255,6 +255,8 @@ void gma_crtc_dpms(struct drm_crtc *crtc, int mode)
> >                 /* Give the overlay scaler a chance to enable
> >                  * if it's on this pipe */
> >                 /* psb_intel_crtc_dpms_video(crtc, true); TODO */
> > +
> > +               drm_crtc_vblank_on(crtc);
> >                 break;
> >         case DRM_MODE_DPMS_OFF:
> >                 if (!gma_crtc->active)
> > --
> > 2.23.0
> >

-- 
Paul Kocialkowski, Bootlin
Embedded Linux and kernel engineering
https://bootlin.com

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