[PATCH i-g-t 3/3] tests/i915/kms_flip_tiling: Fix pageflip timeout for low vrefresh modes

[Imre Deak]

On Fri, Nov 15, 2024 at 05:14:22PM +0530, Sharma, Swati2 wrote:
> Hi Imre,
> 
> Do we have some gitlab issue associated with this fix?

Not sure if there is, the problem needs a mode with a vrefresh rate <
60Hz (to be added to CI for an MST config at least).

> 
> On 22-10-2024 09:23 pm, Imre Deak wrote:
> > The current fixed 50 ms timeout for pageflip completion is not long
> > enough for low vrefresh modes. In general the timeout should account for
> > one frame for the flip itself + one frame for vblank waiting due to FBC
> > invalidation + a fixed amount for scheduling overhead delivering the
> > completion event to userspace. For the usual 60Hz modes the 50 ms
> > timeout worked ok based on the above (2 * 17 ms + 16 ms), but didn't
> > work for 30 Hz modes (the minimum timeout for those being ~67 ms).
> > 
> > Based on the above use a timeout length of 2 * mode specific frame
> > time + 20 ms fixed scheduling delay.
> > 
> > Testcase: igt at kms_flip_tiling
> > Signed-off-by: Imre Deak <imre.deak at intel.com>
> > ---
> >   tests/intel/kms_flip_tiling.c | 14 +++++++++++++-
> >   1 file changed, 13 insertions(+), 1 deletion(-)
> > 
> > diff --git a/tests/intel/kms_flip_tiling.c b/tests/intel/kms_flip_tiling.c
> > index 3bf02564e..e937c2171 100644
> > --- a/tests/intel/kms_flip_tiling.c
> > +++ b/tests/intel/kms_flip_tiling.c
> > @@ -86,6 +86,18 @@ static int try_commit(igt_display_t *display)
> >   				       COMMIT_ATOMIC : COMMIT_LEGACY);
> >   }
> > +static uint64_t pageflip_timeout_us(drmModeModeInfo *mode)
> > +{
> > +	uint64_t timeout_ns;
> > +
> > +	/* 1 frame for flip + 1 frame for vblank wait due to FBC. */
> > +	timeout_ns = igt_kms_frame_time_from_vrefresh(mode->vrefresh) * 2;
> > +	/* 20 msec scheduling overhead. */
> > +	timeout_ns += 20000000;
> > +
> > +	return DIV_ROUND_UP(timeout_ns, 1000);
> > +}
> > +
> >   static void
> >   test_flip_tiling(data_t *data, enum pipe pipe, igt_output_t *output, uint64_t modifier[2])
> >   {
> > @@ -137,7 +149,7 @@ test_flip_tiling(data_t *data, enum pipe pipe, igt_output_t *output, uint64_t mo
> >   	igt_require(ret == 0);
> >   	data->flipevent_in_queue = true;
> > -	kmstest_wait_for_pageflip(data->drm_fd);
> > +	kmstest_wait_for_pageflip_timeout(data->drm_fd, pageflip_timeout_us(mode));
> >   	data->flipevent_in_queue = false;
> >   	/* Get a crc and compare with the reference. */