[PATCH v3 4/8] drm/sun4i: backend: Assign the pipes automatically

[Chen-Yu Tsai]

On Sat, Feb 17, 2018 at 1:39 AM, Maxime Ripard
<maxime.ripard at bootlin.com> wrote:
> Since we now have a way to enforce the zpos, check for the number of alpha
> planes, the only missing part is to assign our pipe automatically instead
> of hardcoding it.
>
> The algorithm is quite simple, but requires two iterations over the list of
> planes.
>
> In the first one (which is the same one that we've had to check for alpha,
> the frontend usage, and so on), we order the planes by their zpos.
>
> We can then do a second iteration over that array by ascending zpos
> starting with the pipe 0. When and if we encounter our alpha plane, we put
> it and all the other subsequent planes in the second pipe.
>
> Signed-off-by: Maxime Ripard <maxime.ripard at bootlin.com>

Reviewed-by: Chen-Yu Tsai <wens at csie.org>