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From: Thierry Reding <thierry.reding@gmail.com>
To: "Michel Dänzer" <michel@daenzer.net>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>,
	Intel Graphics Development <intel-gfx@lists.freedesktop.org>,
	DRI Development <dri-devel@lists.freedesktop.org>
Subject: Re: [PATCH 7/8] drm/irq: Implement a generic vblank_wait function
Date: Wed, 30 Jul 2014 16:20:25 +0200	[thread overview]
Message-ID: <20140730142024.GO29590@ulmo> (raw)
In-Reply-To: <53D8AD9C.7000006@daenzer.net>


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On Wed, Jul 30, 2014 at 05:32:28PM +0900, Michel Dänzer wrote:
> On 30.07.2014 17:22, Daniel Vetter wrote:
> > On Wed, Jul 30, 2014 at 11:59:33AM +0900, Michel Dänzer wrote:
> >> On 30.07.2014 06:32, Daniel Vetter wrote:
> >>> + * due to lack of driver support or because the crtc is off.
> >>> + */
> >>> +void drm_crtc_vblank_wait(struct drm_crtc *crtc)
> >>> +{
> >>> +	drm_vblank_wait(crtc->dev, drm_crtc_index(crtc));
> >>> +}
> >>> +EXPORT_SYMBOL(drm_crtc_vblank_wait);
> >>> +
> >>> +/**
> >>
> >> Maybe the function names should be *_vblank_wait_next() or something to
> >> clarify the purpose and reduce potential confusion versus drm_wait_vblank().
> > 
> > Yeah that name is just transferred from the i915 driver. What about
> > drm_wait_one_vblank()/drm_crtc_wait_one_vblank()?
> 
> I don't care that much :), go ahead.

Just my two cents: our downstream kernel has a helper somewhat like this
which waits for a specified number of frames (apparently this is useful
for some panels that require up to 5 or 6 frames before they display the
correct image on screen). So perhaps something like this could work:

	void drm_wait_vblank_count(struct drm_device *dev, unsigned int crtc,
				   unsigned int count)
	{
		u32 last;
		int ret;

		ret = drm_vblank_get(dev, crtc);
		if (WARN_ON(ret))
			return;

		while (count--) {
			last = drm_vblank_count(dev, crtc);

			...
		}

		drm_vblank_put(dev, crtc);
	}

Then implement drm_wait_vblank() (or drm_wait_one_vblank()) on top of
that as a special case. Of course one could equally well implement
drm_wait_vblank_count() on top of your drm_wait_{one_,}vblank().

I couldn't think of a safe way to make the above work without the
loop...

Thierry

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  reply	other threads:[~2014-07-30 14:20 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-07-29 21:32 [PATCH 0/8] atomic prep work Daniel Vetter
2014-07-29 21:32 ` [PATCH 1/8] drm: Add drm_plane/connector_index Daniel Vetter
2014-07-29 22:59   ` [Intel-gfx] " Matt Roper
2014-07-30  8:31   ` [PATCH] " Daniel Vetter
2014-07-29 21:32 ` [PATCH 2/8] drm: Move modeset_lock_all helpers to drm_modeset_lock.[hc] Daniel Vetter
2014-07-29 23:27   ` Dave Airlie
2014-07-29 21:32 ` [PATCH 3/8] drm: Handle legacy per-crtc locking with full acquire ctx Daniel Vetter
2014-07-29 23:28   ` Dave Airlie
2014-07-30  8:34   ` [PATCH] " Daniel Vetter
2014-07-29 21:32 ` [PATCH 4/8] drm: Move ->old_fb from crtc to plane Daniel Vetter
2014-07-29 23:30   ` Dave Airlie
2014-07-29 23:46   ` [Intel-gfx] " Matt Roper
2014-07-30  8:14     ` Daniel Vetter
2014-07-30  8:34   ` [PATCH] " Daniel Vetter
2014-07-29 21:32 ` [PATCH 5/8] drm: trylock modest locking for fbdev panics Daniel Vetter
2014-07-30 15:56   ` Matt Roper
2014-07-30 16:12     ` Daniel Vetter
2014-07-29 21:32 ` [PATCH 6/8] drm: Add a plane->reset hook Daniel Vetter
2014-07-29 21:32 ` [PATCH 7/8] drm/irq: Implement a generic vblank_wait function Daniel Vetter
2014-07-30  2:59   ` Michel Dänzer
2014-07-30  8:22     ` Daniel Vetter
2014-07-30  8:32       ` Michel Dänzer
2014-07-30 14:20         ` Thierry Reding [this message]
2014-07-30 14:36           ` [Intel-gfx] " Ville Syrjälä
2014-07-30 15:07             ` Daniel Vetter
2014-07-30 15:21             ` [Intel-gfx] " Thierry Reding
2014-07-31  1:14               ` Michel Dänzer
2014-07-31  7:54                 ` Daniel Vetter
2014-07-31  8:56                   ` Michel Dänzer
2014-07-31  9:46                     ` Daniel Vetter
2014-07-30  9:25   ` [PATCH] " Daniel Vetter
2014-07-30  9:52     ` Michel Dänzer
2014-07-30 14:24   ` [PATCH 7/8] " Thierry Reding
2014-07-30 15:06     ` Daniel Vetter
2014-07-30 15:10       ` Thierry Reding
2014-07-29 21:32 ` [PATCH 8/8] drm/i915: Use generic vblank wait Daniel Vetter
2014-07-30  9:25   ` [PATCH] " Daniel Vetter
2014-07-30 13:36 ` [PATCH] drm: Docbook fixes Daniel Vetter
2014-08-05  2:51   ` [Intel-gfx] " Dave Airlie
2014-08-05  7:28     ` Daniel Vetter

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