Re: [PATCH] drm/syncobj: return meaningful value to user space

[Lionel Landwerlin <lionel.g.landwerlin@intel.com>]

On 18/07/2019 16:02, Chunming Zhou wrote:
> 在 2019/7/18 19:31, Lionel Landwerlin 写道:
>> On 18/07/2019 14:13, Chunming Zhou wrote:
>>> if WAIT_FOR_SUBMIT isn't set and in the meanwhile no underlying fence
>>> on syncobj,
>>> then return non-block error code to user sapce.
>>>
>>> Signed-off-by: Chunming Zhou <david1.zhou@amd.com>
>>> ---
>>>    drivers/gpu/drm/drm_syncobj.c | 4 ++--
>>>    1 file changed, 2 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/drm_syncobj.c
>>> b/drivers/gpu/drm/drm_syncobj.c
>>> index 361a01a08c18..929f7c64f9a2 100644
>>> --- a/drivers/gpu/drm/drm_syncobj.c
>>> +++ b/drivers/gpu/drm/drm_syncobj.c
>>> @@ -252,7 +252,7 @@ int drm_syncobj_find_fence(struct drm_file
>>> *file_private,
>>>                return 0;
>>>            dma_fence_put(*fence);
>>>        } else {
>>> -        ret = -EINVAL;
>>> +        ret = -ENOTBLK;
>>>        }
>>>          if (!(flags & DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT))
>>> @@ -832,7 +832,7 @@ static signed long
>>> drm_syncobj_array_wait_timeout(struct drm_syncobj **syncobjs,
>>>                if (flags & DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT) {
>>>                    continue;
>>>                } else {
>>> -                timeout = -EINVAL;
>>> +                timeout = -ENOTBLK;
>>>                    goto cleanup_entries;
>>>                }
>>>            }
>>
>> This would break existing tests for binary syncobjs.
> How does this breaks binary syncobj?


This is used in the submission path of several drivers.

Changing the error code will change what the drivers are reporting to 
userspace and could break tests.


i915 doesn't use that function so it's not affected but 
lima/panfrost/vc4 seem to be.


>
>
>> Is this really what we want?
> I want to use this meaningful return value to judge if WaitBeforeSignal
> happens.
>
> I think this is the cheapest change for that.


I thought the plan was to add a new ioctl to query the last submitted value.

Did I misunderstand?


Thanks,


-Lionel


>
> -David
>
>
>>
>> -Lionel
>>
>>

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