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

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Date:   Mon, 16 Jan 2017 10:12:36 +0100
From:   Tomeu Vizoso <tomeu.vizoso@...labora.com>
To:     Ville Syrjälä <ville.syrjala@...ux.intel.com>,
        Tomeu Vizoso <tomeu.vizoso@...labora.com>,
        David Airlie <airlied@...ux.ie>,
        Intel Graphics Development <intel-gfx@...ts.freedesktop.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Thierry Reding <thierry.reding@...il.com>,
        "dri-devel@...ts.freedesktop.org" <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 10 January 2017 at 17:31, Daniel Vetter <daniel@...ll.ch> wrote:
> 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.

At least on the SKL and SNB I have here, the -sequence subtests in
kms_pipe_crc_basic fail if I replace the call to
drm_accurate_vblank_count with drm_crtc_vblank_count.

Any ideas on why this could be?

Thanks,

Tomeu