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

[Leo Liu]

On 09/02/2016 02:11 AM, Christian König wrote:
> 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.

Also we have to consider drawable resized case.

Regards,
Leo

> 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.