[igt-dev] [PATCH i-g-t] tests/kms_cursor_legacy: Remove vblank counter check immediately after flip_nonblocking

[Petri Latvala]

On Fri, Dec 10, 2021 at 09:20:06AM -0800, Jessica Zhang wrote:
> Currently, there is a check that the vblank counter shouldn't change after
> a nonblocking page flip and DRM_IOCTL_MODE_CURSOR call. This assumes
> that ioctl is performed before the commit from the nonblocking flip is
> dequeued.
> 
> The DRM_IOCTL_MODE_CURSOR callstack is as such:
> 	drm_mode_cursor_ioctl
> 	drm_mode_cursor_common
> 	drm_mode_cursor_universal
> 	__setplane_atomic
> 	drm_atomic_helper_update_plane
> 	drm_atomic_commit
> 
> Becuase the commit work queue is scheduled earlier than
> DRM_CURSOR_IOCTL, it will finish before the ioctl. Thus, we can't
> assume that the current vblank count will match vblank_start after the
> cursor ioctl finishes.
> 
> Tested-on: Chromebook Lazor (Trogdor)

Does this imply that on this device, the vblank counter increases from
the cursor ioctl?

What remains to be documented here is whether that's an implementation
detail, documentation bug, or a kernel bug. Maybe Ville is able to
understand this better than me.


-- 
Petri Latvala


> 
> Signed-off-by: Jessica Zhang <quic_jesszhan at quicinc.com>
> ---
>  tests/kms_cursor_legacy.c | 2 --
>  1 file changed, 2 deletions(-)
> 
> diff --git a/tests/kms_cursor_legacy.c b/tests/kms_cursor_legacy.c
> index d50155e8..82c01bc8 100644
> --- a/tests/kms_cursor_legacy.c
> +++ b/tests/kms_cursor_legacy.c
> @@ -1307,8 +1307,6 @@ static void flip_vs_cursor_crc(igt_display_t *display, bool atomic)
>  		flip_nonblocking(display, pipe, atomic, &fb_info, NULL);
>  		do_ioctl(display->drm_fd, DRM_IOCTL_MODE_CURSOR, &arg[i]);
>  
> -		igt_assert_eq(kmstest_get_vblank(display->drm_fd, pipe, 0), vblank_start);
> -
>  		igt_set_timeout(1, "Stuck page flip");
>  		igt_ignore_warn(read(display->drm_fd, &vbl, sizeof(vbl)));
>  		igt_reset_timeout();
> -- 
> 2.31.0
>