Re: [PATCH 03/12] media: hantro: Fix H264 motion vector buffer offset

[Ezequiel Garcia]

Hi Jonas,

Thanks for fixing this, I'm happy we are reducing the amount
of black magic here.

On Sun, 2019-09-01 at 12:45 +0000, Jonas Karlman wrote:
> A decoded 8-bit 4:2:0 frame need memory for up to 448 macroblocks
> and is laid out in memory as follow:
> 
> +-------------------+
> > Y-plane   256 MBs |
> +-------------------+
> > UV-plane  128 MBs |
> +-------------------+
> > MV buffer  64 MBs |
> +-------------------+
> 
> The motion vector buffer offset is currently correct for 4:2:0 because
> the extra space for motion vectors is overallocated with an extra 64 MBs.
> 
> Wrong offset for both destination and motion vector buffer are used
> for the bottom field of field encoded content, wrong offset is
> also used for 4:0:0 (monochrome) content.
> 
> Fix this by always setting the motion vector address to the expected
> 384 MBs offset for 4:2:0 and 256 MBs offset for 4:0:0 content.
> 
> Also use correct destination and motion vector buffer offset
> for the bottom field of field encoded content.
> 
> While at it also extend the check for 4:0:0 (monochrome) to include an
> additional check for High Profile (100).
> 

As with the scaling list, I believe it would make a lot of sense
to document this in the driver itself.

Thanks,
Ezequiel