[PATCH v3] drm/fourcc: document modifier uniqueness requirements

[Alex Deucher]

On Fri, May 29, 2020 at 10:32 AM Daniel Stone <daniel at fooishbar.org> wrote:
>
> On Fri, 29 May 2020 at 15:29, Alex Deucher <alexdeucher at gmail.com> wrote:
> > Maybe I'm over thinking this.  I just don't want to get into a
> > situation where we go through a lot of effort to add modifier support
> > and then performance ends up being worse than it is today in a lot of
> > cases.
>
> I'm genuinely curious: what do you imagine could cause a worse result?

As an example, in some cases, it's actually better to use linear for
system memory because it better aligns with pcie access patterns than
some tiling formats (which are better aligned for the memory
controller topology on the dGPU).  That said, I haven't been in the
loop as much with the tiling formats on newer GPUs, so that may not be
as much of an issue anymore.

Alex