[igt-dev] [PATCH i-g-t] igt/gem_mmap_gtt: Check for known incoherency before testing

[Tvrtko Ursulin]

On 20/07/2018 09:07, Chris Wilson wrote:
> We test map_gtt coherency (whether or not a write via the mmap_gtt is
> immediately visible in the backing storage to a read via mmap_cpu) but
> we know that several platforms are inherently incorrect and require some
> form of hammer to workaround internal delays. These platforms break our
> ABI guarantees and so we report the change in ABI via a driver getparam.
> 
> If we know the platform doesn't meet the ABI guarantee, skip the test.
> If it is meant to work, test!
> 
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
> ---
>   tests/gem_mmap_gtt.c | 13 +++++++++++++
>   1 file changed, 13 insertions(+)
> 
> diff --git a/tests/gem_mmap_gtt.c b/tests/gem_mmap_gtt.c
> index c8a0bedec..f63535556 100644
> --- a/tests/gem_mmap_gtt.c
> +++ b/tests/gem_mmap_gtt.c
> @@ -309,6 +309,18 @@ test_write_gtt(int fd)
>   	munmap(src, OBJECT_SIZE);
>   }
>   
> +static bool is_coherent(int i915)
> +{
> +	int val = 1; /* by default, we assume GTT is coherent, hence the test */
> +	struct drm_i915_getparam gp = {
> +		gp.param = 52, /* GTT_COHERENT */
> +		gp.value = &val,
> +	};
> +
> +	ioctl(i915, DRM_IOCTL_I915_GETPARAM, &gp);
> +	return val;
> +}
> +
>   static void
>   test_coherency(int fd)
>   {
> @@ -316,6 +328,7 @@ test_coherency(int fd)
>   	uint32_t *gtt, *cpu;
>   	int i;
>   
> +	igt_require(is_coherent(fd));
>   	igt_require(igt_setup_clflush());
>   
>   	handle = gem_create(fd, OBJECT_SIZE);
> 

Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>

Regards,

Tvrtko