[igt-dev] [PATCH i-g-t] tests/kms_plane_lowres: Skip if no suitable mode is possible

[Ser, Simon]

On Tue, 2019-08-20 at 07:19 -0700, Matt Roper wrote:
> When choosing a low resolution mode to switch to, we search the
> connector's mode list for a mode that's small enough that a plane
> positioned in the bottom left corner of the screen in the original mode
> will be fully offscreen in the new, smaller mode.  However if no
> suitable modes are found in the modelist, we blindly fall back to a 10x7
> mode without actually checking that the canary plane will now be
> offscreen.  If, for example, the original mode was 13x7, then switching
> to 10x7 will leave the plane visible onscreen, causing the test to fail.
> 
> Before falling back to a 10x7 mode, check whether that's actually small
> enough.  If it isn't just skip this subtest.
> 
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=105581
> Signed-off-by: Matt Roper <matthew.d.roper at intel.com>
> ---
>  tests/kms_plane_lowres.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/tests/kms_plane_lowres.c b/tests/kms_plane_lowres.c
> index 68b85025..3f20ed32 100644
> --- a/tests/kms_plane_lowres.c
> +++ b/tests/kms_plane_lowres.c
> @@ -59,8 +59,10 @@ get_lowres_mode(int drmfd, igt_output_t *output, drmModeModeInfo *mode_default)
>  		}
>  	}
>  
> -	if (!found)
> +	if (!found) {
> +		igt_skip_on(limit <= 768);

Instead of hardcoding 768, can we use 1024 - SIZE? This would make it
clearer where this value comes from.

>  		return *igt_std_1024_mode_get();
> +	}
>  
>  	return mode;
>  }