Re: [PATCH] drm: add modifiers for MediaTek tiled formats

[Daniel Stone]

Hey Eric,

On Thu, 19 Dec 2024 at 00:20, Eric Smith <eric.smith@xxxxxxxxxxxxx> wrote:
> On 18/12/2024 10.33, Daniel Stone wrote:
> >> +/*
> >> + * MediaTek Tiled Modifier
> >> + * This is a tiled layout using tiles of 16x32 pixels in a row-major layout.
> >> + * For chroma planes this becomes 16x16 tiles.
> >> + */
> >> +#define DRM_FORMAT_MOD_MTK_16L_32S_TILE  fourcc_mod_code(MTK, (1ULL << 0))
> > I think this probably wants to be something like the tiling mode
> > defined in AMD/Arm modifiers, i.e. reserve a few bits in the range to
> > select the tile size, rather than using a single bit here.
>
> Thank you for taking the time, and for your suggestions. Are you
> thinking something along the lines of:
>
> [...]

Yeah, that's exactly it. You could even push the boat out and widen
the fields a little bit to give more headroom; if you want to change
the layout because you want to add more flags or whatever, you can
just do what Arm did, and take the top couple of bits as a layout
version or epoch.

Cheers,
Daniel