[igt-dev] [PATCH v2 1/1] tests/kms_cursor_legacy: Skip 2x-cursor-vs-flip subtests for gen > 9

[Ville Syrjälä]

On Tue, Mar 12, 2019 at 09:12:44AM -0700, Neel Desai wrote:
> Due to DDB allocation changes, we have to add all the planes to the
> drm_atomic_state post gen 9.

As we discussed on irc that is not true. The cursor has a fixed
allocation and thus never needs to be added to the state on account
of ddb allocation changing (except for full modesets). So the real
reason for the cursor being added to the state is something else.
I think the answer has something more to do with the selected
max watermark level.

Also I'm not entirely convinced that the fixed allocation scheme
is working quite right currently. We never seem to check that we
actually have enough ddb space for the selected max watermark
level for the cursor. We should add such a check, and we also may
have to change how we calculate the size of the fixed cursor ddb
allocation to make sure the cursor isn't needlessly limiting the
max watermark level we can use.

> When the watermarks are computed by the
> kernel, the cursor plane is added to the drm_atomic_state which
> introduces a dependency on hw_done object when the kernel processes
> DRM_IOCTL_MODE_ATOMIC and DRM_IOCTL_MODE_CURSOR in parallel. There is no
> race-free way to handle this corner case. These subtests made sense for
> older generations but not anymore. Hence, skipping these sub-tests post
> gen 9.
> 
> Reference: https://bugs.freedesktop.org/show_bug.cgi?id=109079
> Signed-off-by: Neel Desai <neel.desai at intel.com>
> cc: Sudeep Dutt <sudeep.dutt at intel.com>
> cc: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
> ---
>  tests/kms_cursor_legacy.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/tests/kms_cursor_legacy.c b/tests/kms_cursor_legacy.c
> index d6987eea..645c0b93 100644
> --- a/tests/kms_cursor_legacy.c
> +++ b/tests/kms_cursor_legacy.c
> @@ -1115,6 +1115,7 @@ static void cursor_vs_flip(igt_display_t *display, enum flip_test mode, int nloo
> 
>  static void two_screens_cursor_vs_flip(igt_display_t *display, int nloops, bool atomic)
>  {
> +	const int gen = intel_gen(intel_get_drm_devid(display->drm_fd));
>  	struct drm_mode_cursor arg[2][2];
>  	struct drm_event_vblank vbl;
>  	struct igt_fb fb_info[2], cursor_fb;
> @@ -1126,6 +1127,8 @@ static void two_screens_cursor_vs_flip(igt_display_t *display, int nloops, bool
>  	};
>  	igt_output_t *outputs[2];
> 
> +	igt_require(gen <= 9);
> +
>  	shared = mmap(NULL, PAGE_SIZE, PROT_WRITE, MAP_SHARED | MAP_ANON, -1, 0);
>  	igt_assert(shared != MAP_FAILED);
> 
> --
> 2.17.1
> 
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-- 
Ville Syrjälä
Intel