linux-kernel - Re: [Intel-gfx] [RESEND PATCH v14 2/2] drm/i915: Put "cooked" vlank counters in frame CRC lines

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Message-ID: <20170110163149.xb7ysmfs5knvzxeu@phenom.ffwll.local>
Date:   Tue, 10 Jan 2017 17:31:49 +0100
From:   Daniel Vetter <daniel@...ll.ch>
To:     Ville Syrjälä <ville.syrjala@...ux.intel.com>
Cc:     Tomeu Vizoso <tomeu.vizoso@...labora.com>,
        David Airlie <airlied@...ux.ie>,
        intel-gfx@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        Thierry Reding <thierry.reding@...il.com>,
        dri-devel@...ts.freedesktop.org,
        Daniel Vetter <daniel.vetter@...el.com>
Subject: Re: [Intel-gfx] [RESEND PATCH v14 2/2] drm/i915: Put "cooked" vlank
 counters in frame CRC lines

On Tue, Jan 10, 2017 at 05:54:57PM +0200, Ville Syrjälä wrote:
> On Tue, Jan 10, 2017 at 02:43:05PM +0100, Tomeu Vizoso wrote:
> > Use drm_accurate_vblank_count so we have the full 32 bit to represent
> > the frame counter and userspace has a simpler way of knowing when the
> > counter wraps around.
> > 
> > Signed-off-by: Tomeu Vizoso <tomeu.vizoso@...labora.com>
> > Reviewed-by: Emil Velikov <emil.velikov@...labora.com>
> > Reviewed-by: Robert Foss <robert.foss@...labora.com>
> > ---
> > 
> >  drivers/gpu/drm/i915/i915_irq.c | 6 +++---
> >  1 file changed, 3 insertions(+), 3 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
> > index b9beb5955dae..75fb1f66cc0c 100644
> > --- a/drivers/gpu/drm/i915/i915_irq.c
> > +++ b/drivers/gpu/drm/i915/i915_irq.c
> > @@ -1557,7 +1557,6 @@ static void display_pipe_crc_irq_handler(struct drm_i915_private *dev_priv,
> >  	struct drm_driver *driver = dev_priv->drm.driver;
> >  	uint32_t crcs[5];
> >  	int head, tail;
> > -	u32 frame;
> >  
> >  	spin_lock(&pipe_crc->lock);
> >  	if (pipe_crc->source) {
> > @@ -1612,8 +1611,9 @@ static void display_pipe_crc_irq_handler(struct drm_i915_private *dev_priv,
> >  		crcs[2] = crc2;
> >  		crcs[3] = crc3;
> >  		crcs[4] = crc4;
> > -		frame = driver->get_vblank_counter(&dev_priv->drm, pipe);
> > -		drm_crtc_add_crc_entry(&crtc->base, true, frame, crcs);
> > +		drm_crtc_add_crc_entry(&crtc->base, true,
> > +				       drm_accurate_vblank_count(&crtc->base),
> 
> My assumption would be that this gets called after the vblank irq
> handler, so using the _accurate version seems a bit overkill.

Since we're at like v15 of this I figured I'll pull this in, and we can
polish this a bit more later. Tomeu, can you pls do that follow-up patch
and get Ville to review+merge it.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch