[Intel-gfx] [PATCH i-g-t] kms_flip_tiling: [linear, X]<->[Y, Yf] tiling changes are not allowed

[Chris Wilson]

On Wed, Apr 22, 2015 at 05:23:11PM +0100, Tvrtko Ursulin wrote:
> 
> Hi,
> 
> On 04/22/2015 05:07 PM, Chris Wilson wrote:
> >On Wed, Apr 22, 2015 at 05:00:27PM +0100, Tvrtko Ursulin wrote:
> >>From: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> >>
> >>This matches the behaviour in kernel patch
> >>"drm/i915/skl: Disallow tiling changes during page flip".
> >>
> >>Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> >>Cc: Chris Wilson <chris at chris-wilson.co.uk>
> >>---
> >>  tests/kms_flip_tiling.c | 23 ++++++++++++++---------
> >>  1 file changed, 14 insertions(+), 9 deletions(-)
> >>
> >>diff --git a/tests/kms_flip_tiling.c b/tests/kms_flip_tiling.c
> >>index 8345505..3eef4cc 100644
> >>--- a/tests/kms_flip_tiling.c
> >>+++ b/tests/kms_flip_tiling.c
> >>@@ -63,7 +63,7 @@ fill_linear_fb(struct igt_fb *fb, data_t *data, drmModeModeInfo *mode)
> >>  }
> >>
> >>  static void
> >>-test_flip_changes_tiling(data_t *data, igt_output_t *output, uint64_t tiling)
> >>+test_flip_changes_tiling(data_t *data, igt_output_t *output, uint64_t tiling, int expect)
> >>  {
> >>  	struct igt_fb linear, tiled;
> >>  	drmModeModeInfo *mode;
> >>@@ -107,13 +107,15 @@ test_flip_changes_tiling(data_t *data, igt_output_t *output, uint64_t tiling)
> >>  	/* flip to the linear buffer */
> >>  	ret = drmModePageFlip(data->drm_fd, output->config.crtc->crtc_id,
> >>  			      fb_id, 0, NULL);
> >>-	igt_assert_eq(ret, 0);
> >>+	igt_assert_eq(ret, expect);
> >>
> >>-	igt_wait_for_vblank(data->drm_fd, pipe);
> >>+	if (expect == 0) {
> >
> >I'd still accept ret == 0 since maybe one day it will work happily.
> >
> >So perhaps:
> >if (ret) igt_assert_rq(ret, expect);
> >igt_require(ret == 0);
> >?
> 
> Well would have to at least run the cleanup part before skipping,
> but even before that I am not sure. That means test would skip
> today, and who knows for how long in the future, and then soon no
> one kind of knows what that means - is it good or bad?

The other side of the coin is that the test implies such tiling changes
are verboten, which is just an implementation detail of today's kernel
and also not guaranteed to stay the same.

I'd rather see a test ready for checking Y-tiled flipping so that should
someone try and decide to run this test, they are not immediately
disappointed. Also it should show the bug in current kernels.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre