[Mesa-dev] [PATCH 2/2] st/vdapu: use lanczos filter for scaling v4

[Christian König]

Am 02.09.2016 um 04:03 schrieb Michel Dänzer:
> On 02/09/16 10:17 AM, Michel Dänzer wrote:
>> On 02/09/16 12:58 AM, Leo Liu wrote:
>>> On 09/01/2016 11:54 AM, Nayan Deshmukh wrote:
>>>> I saw the code in dri3_glx.c and I could somewhat relate some basic
>>>> code structure to the vl_winsys_dri3.c. But I am new to this and not aware of the
>>>> terminology that you used about the buffers. Could you please explain what needs
>>>> to be done in more detail or point me to where I can read about it.
>>> I believe it's from loader_dri3_helper.c with "is_different_gpu"
>>> condition true, that will include back buffer and front buffer case.
>>> you could try only back buffer case for now.
>>  From a high level, PRIME mainly affects presentation, not so much the
>> video decoding / rendering. The important thing is that the buffer used
>> for presentation via the Present extension is linear, not tiled. I'm not
>> sure whether it makes more sense to allocate a separate linear buffer
>> for this purpose, as is done for GLX, or for the vl code to make the
>> corresponding back (or front?) buffer linear in the first place.
> A separate linear buffer is probably better, actually, since it will
> also be pinned to system memory while it's being shared with another GPU.

Yes, I agree. Nayan should also work on avoiding the extra copy which 
currently occur because we can't allocate output buffers directly in the 
format needed for presentation.

The general idea should be to to check during presentation if the format 
in the output surface is displayable directly. If that is the case then 
handle of that surface should be send directly to X.
If that isn't the case we reallocate the backing buffer, copy the 
content of the output surface into it and then send the new handle to X.

Regards,
Christian.