Re: [PATCH] drm/i915/selftests: Set always_coherent to false when reading from CPU

[Jani Nikula <jani.nikula@linux.intel.com>]

On Fri, 17 May 2024, Nirmoy Das <nirmoy.das@linux.intel.com> wrote:
> Hi Jani,
>
> On 5/17/2024 9:39 AM, Jani Nikula wrote:
>> On Thu, 16 May 2024, Nirmoy Das <nirmoy.das@intel.com> wrote:
>>> The previous commit 'commit 8d4ba9fc1c6c ("drm/i915/selftests: Pick
>> "previous commit" is a fairly vague reference once this gets
>> committed. It's not going to be "previous" in any meaningful sense.
>>
>> Please just start with:
>>
>> Commit 8d4ba9fc1c6c ("drm/i915/selftests: Pick correct caching mode.")
>> was not complete...
>
> Will do that.
>
>
>>
>> And probably add:
>>
>> Fixes: 8d4ba9fc1c6c ("drm/i915/selftests: Pick correct caching mode.")
>
> Do we need Fixes for selftest ? I always assumed it is not required as 
> this code is for debug/CI

Maybe not for stuff that's already in stable, but we do run CI on
drm-next and -rc kernels, and if this causes issues there, why not have
them fixed?

BR,
Jani.

>
>
> Thanks,
>
> Nirmoy
>
>>
>> BR,
>> Jani.
>>
>>> correct caching mode.")' was not complete as for non LLC  sharing platforms
>>> cpu read can happen from LLC which probably doesn't have the latest
>>> changes made by GPU.
>>>
>>> Cc: Andi Shyti <andi.shyti@linux.intel.com>
>>> Cc: Janusz Krzysztofik <janusz.krzysztofik@linux.intel.com>
>>> Cc: Jonathan Cavitt <jonathan.cavitt@intel.com>
>>> Signed-off-by: Nirmoy Das <nirmoy.das@intel.com>
>>> ---
>>>   drivers/gpu/drm/i915/gem/selftests/i915_gem_dmabuf.c | 2 +-
>>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/gpu/drm/i915/gem/selftests/i915_gem_dmabuf.c b/drivers/gpu/drm/i915/gem/selftests/i915_gem_dmabuf.c
>>> index 65a931ea80e9..3527b8f446fe 100644
>>> --- a/drivers/gpu/drm/i915/gem/selftests/i915_gem_dmabuf.c
>>> +++ b/drivers/gpu/drm/i915/gem/selftests/i915_gem_dmabuf.c
>>> @@ -196,7 +196,7 @@ static int verify_access(struct drm_i915_private *i915,
>>>   	if (err)
>>>   		goto out_file;
>>>   
>>> -	mode = intel_gt_coherent_map_type(to_gt(i915), native_obj, true);
>>> +	mode = intel_gt_coherent_map_type(to_gt(i915), native_obj, false);
>>>   	vaddr = i915_gem_object_pin_map_unlocked(native_obj, mode);
>>>   	if (IS_ERR(vaddr)) {
>>>   		err = PTR_ERR(vaddr);

-- 
Jani Nikula, Intel