Re: [igt-dev] [PATCH i-g-t] tests/kms: Return false in gem_has_lmem for platforms not having LMEM support

["Dixit, Ashutosh" <ashutosh.dixit@intel.com>]

On Fri, 23 Jul 2021 02:35:48 -0700, Vidya Srinivas wrote:
>
> Starting commit (tests/kms: Create buffer object from LMEM for discrete) it checks
> for LMEM. But this is breaking older kernels like 5.4 without
> DRM_I915_QUERY_MEMORY_REGIONS support. This causes
> item.length filled from IOCTL to be < 0 and gives segmentation
> fault. Another way to fix is check for NULL query in
> gem_get_lmem_region_count and return false.
>
> Patch returns false from gem_has_lmem for obvious platforms
> which dont have LMEM support and also adds the check
> for NULL query in gem_get_lmem_region_count.
>
> Signed-off-by: Lin Charlton <charlton.lin@intel.com>
> Signed-off-by: Vidya Srinivas <vidya.srinivas@intel.com>
> ---
>  lib/i915/intel_memory_region.c | 7 +++++++
>  1 file changed, 7 insertions(+)
>
> diff --git a/lib/i915/intel_memory_region.c b/lib/i915/intel_memory_region.c
> index 144ae12ca7a0..635c21ab3765 100644
> --- a/lib/i915/intel_memory_region.c
> +++ b/lib/i915/intel_memory_region.c
> @@ -143,6 +143,10 @@ uint8_t gem_get_lmem_region_count(int fd)
>	uint8_t lmem_regions = 0;
>
>	query_info = gem_get_query_memory_regions(fd);
> +
> +	if (!query_info)
> +		return 0;

From the code doesn't look like this works.

> +
>	num_regions = query_info->num_regions;
>
>	for (int i = 0; i < num_regions; i++) {
> @@ -164,6 +168,9 @@ uint8_t gem_get_lmem_region_count(int fd)
>   */
>  bool gem_has_lmem(int fd)
>  {
> +	if (intel_display_ver(intel_get_drm_devid(fd) < 12) ||
> +		IS_ALDERLAKE_P(intel_get_drm_devid(fd)) || IS_TIGERLAKE(intel_get_drm_devid(fd)))
> +		return false;

No platform checks. Check if DRM_I915_QUERY_MEMORY_REGIONS is not supported
and in that case return 0 from gem_get_lmem_region_count.

>	return gem_get_lmem_region_count(fd) > 0;
>  }
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