Re: [PATCH i-g-t] tests/intel/xe_vm: Fix WB caching PAT index for coherency mode

[Matthew Auld <matthew.auld@intel.com>]

On 25/03/2024 21:27, Jagmeet Randhawa wrote:
> Resolve a coherency conflict by setting the
> correct PAT index for WB caching with
> intel_get_pat_idx_wb(fd), addressing the
> mismatch between the default "XE_COH_NONE"
> coherency mode and DRM_XE_GEM_CPU_CACHING_WB.

Could maybe reword to something like:

"Ensure we set a suitable default pat_index, which is always compatible 
with any CPU caching mode, like intel_get_pat_idx_wb(). For example, 
currently we are blindly selecting pat_index=0 which has COH_NONE on LNL 
and then attempting to use that with CPU caching mode WB, which is not 
supported by the KMD."

> This conflict occurs for VLK:54352.
> 
> Cc: Jonathan Cavitt <jonathan.cavitt@intel.com>
> Cc: Matthew Auld <matthew.auld@intel.com>
> Cc: Oak Zeng <oak.zeng@intel.com>
> Signed-off-by: Jagmeet Randhawa <jagmeet.randhawa@intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>

> ---
>   tests/intel/xe_vm.c | 1 +
>   1 file changed, 1 insertion(+)
> 
> diff --git a/tests/intel/xe_vm.c b/tests/intel/xe_vm.c
> index 7c061c497..1f458174d 100644
> --- a/tests/intel/xe_vm.c
> +++ b/tests/intel/xe_vm.c
> @@ -1789,6 +1789,7 @@ static void bind_flag_invalid(int fd)
>   	bind.bind.range = bo_size;
>   	bind.bind.addr = addr;
>   	bind.bind.op = DRM_XE_VM_BIND_OP_MAP;
> +	bind.bind.pat_index = intel_get_pat_idx_wb(fd);
>   	bind.num_syncs = 1;
>   	bind.syncs = (uintptr_t)sync;
>