Re: [RFC][PATCH 05/15] videobuf2: handle V4L2_FLAG_MEMORY_NON_CONSISTENT in REQBUFS

[Hans Verkuil]

On 1/22/20 4:48 AM, Sergey Senozhatsky wrote:
> On (20/01/22 11:18), Sergey Senozhatsky wrote:
> [..]
>>>> +    * -
>>>> +      - __u32
>>>>        - ``reserved``\ [1]
>>>>        - A place holder for future extensions. Drivers and applications
>>>> -	must set the array to zero.
>>>> +	must set the array to zero, unless application wants to specify
>>>> +        buffer management ``flags``.
>>>
>>> I think support for this flag should be signaled as a V4L2_BUF_CAP capability.
>>> If the capability is not set, then vb2 should set 'flags' to 0 to preserve the
>>> old 'Drivers and applications must set the array to zero' behavior.
>>
>> The patch set adds V4L2_BUF_CAP_SUPPORTS_CACHE_HINTS towards the end of the
>> series, I guess I can shuffle the patches and change the wording here.
> 
> Or I can add separate queue flag and V4L2_BUF_CAP:
> 
> struct vb2_queue {
> ...
> 	allow_cache_hints:1
> +	allow_consistency_hints:1
> ...
> }
> 
> and then have CAP_SUPPORTS_CACHE_HINTS/CAP_SUPPORTS_CONSISTENCY_HINTS.

Don't these two go hand-in-hand? I.e. either neither are supported, or
both are supported? If so, then one queue flag is sufficient.

Regards,

	Hans

> 
> 	-ss
>