Re: [PATCH] drm/meson: Reduce the FIFO lines held when AFBC is not used

[Martin Blumenstingl]

Hi Carlo,

On Mon, Dec 19, 2022 at 9:43 AM Carlo Caione <ccaione@xxxxxxxxxxxx> wrote:
>
> Having a bigger number of FIFO lines held after vsync is only useful to
> SoCs using AFBC to give time to the AFBC decoder to be reset, configured
> and enabled again.
>
> For SoCs not using AFBC this, on the contrary, is causing on some
> displays issues and a few pixels vertical offset in the displayed image.
On the 32-bit SoCs (for which VPU support is not upstream yet) it has
caused screen tearing instead of shifting the image.

> Conditionally increase the number of lines held after vsync only for
> SoCs using AFBC, leaving the default value for all the others.
That was also my approach (for a not-yet-upstream patch).
Since it's affecting already supported SoCs I suggest adding
"Fixed-by: 24e0d4058eff ..." (maybe Neil can do so when he agrees and
is applying the patch).

Acked-by: Martin Blumenstingl <martin.blumenstingl@xxxxxxxxxxxxxx>