Re: [PATCH] drm/xe/query: Only advertise NO_COMPRESSION hint on devices with flat CCS

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

On 05/02/2026 13:43, Souza, Jose wrote:
> On Thu, 2026-02-05 at 13:50 +0530, Sanjay Yadav wrote:
>> Devices like CRI have GRAPHICS_VER >= 20 but don't have compression
>> support their PAT table (xe3p_xpc_pat_table) has no compression-
>> enabled
>> entries.
>>
>> Only advertise HAS_NO_COMPRESSION_HINT flag when the device actually
>> has
>> flat CCS and thus compression capability.
> 
> Is this change required to fix a bug? Semantically, it doesn't make
> much sense. If a device doesn't support compression and we pass
> DRM_XE_GEM_CREATE_FLAG_NO_COMPRESSION during BO creation, I don't see a
> problem with it. You could optimize and always enable this flag
> internally for this device, but passing it during creation isn't wrong.

Yeah, there is no real bug. But having HAS_NO_COMPRESSION return false 
to reflect that tagging buffers with NO_COMPRESSION is not 
relevant/needed on this device, since compression as a feature is either 
disabled or does not even exist in the hw, also seems reasonable.

The motivation was originally IGT, just to make it a bit simpler to 
detect when this flag is bogus, on certain platforms. And from UMD pov 
having it more accurately reflect whether using this flag is relevant or 
not seemed reasonable.

We can try to so fix the IGT issue in another way, without touching this 
flag, if preferred.

> 
>>
>> Fixes: 78d91ba6bd796 ("drm/xe/uapi: Add NO_COMPRESSION BO flag and
>> query capability")
>> Cc: Matthew Auld <matthew.auld@intel.com>
>> Cc: José Roberto de Souza <jose.souza@intel.com>
>> Cc: Stuart Summers <stuart.summers@intel.com>
>> Signed-off-by: Sanjay Yadav <sanjay.kumar.yadav@intel.com>
>> ---
>>   drivers/gpu/drm/xe/xe_query.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/gpu/drm/xe/xe_query.c
>> b/drivers/gpu/drm/xe/xe_query.c
>> index 34db266b723f..c152ebfbd7d8 100644
>> --- a/drivers/gpu/drm/xe/xe_query.c
>> +++ b/drivers/gpu/drm/xe/xe_query.c
>> @@ -335,7 +335,7 @@ static int query_config(struct xe_device *xe,
>> struct drm_xe_device_query *query)
>>   	if (xe->info.has_usm && IS_ENABLED(CONFIG_DRM_XE_GPUSVM))
>>   		config->info[DRM_XE_QUERY_CONFIG_FLAGS] |=
>>   			DRM_XE_QUERY_CONFIG_FLAG_HAS_CPU_ADDR_MIRROR
>> ;
>> -	if (GRAPHICS_VER(xe) >= 20)
>> +	if (GRAPHICS_VER(xe) >= 20 && xe_device_has_flat_ccs(xe))
>>   		config->info[DRM_XE_QUERY_CONFIG_FLAGS] |=
>>   			DRM_XE_QUERY_CONFIG_FLAG_HAS_NO_COMPRESSION_
>> HINT;
>>   	config->info[DRM_XE_QUERY_CONFIG_FLAGS] |=