Re: [PATCH v5 0/3] Add "link bpc" DRM property

[Daniel Stone]

Hi,

On Wed, 1 Apr 2026 at 12:10, Ville Syrjälä
<ville.syrjala@xxxxxxxxxxxxxxx> wrote:
> On Wed, Apr 01, 2026 at 09:40:15AM +0100, Daniel Stone wrote:
> > The end game of this isn't Weston logging something to stdout, it's to
> > surface things to userspace so it can guide the kernel into making a
> > good decision for usecases that may not be ones the silicon vendor
> > decided was 'probably the best thing' however many years ago.
>
> I think the problem here is that no one even tried to make a
> real userspace implementation. So it's very hard to judge if this
> new property is actually usable in the end, or if it will just end
> up as historical baggage that we have to carry around forever.
>
> IMO just having userspace log what the kernel said does not fulfill
> the "userspace implementation must be ready before new drm uapi is
> merged" requirement.

Sure. To be honest it seemed pretty obviously reflective of 'max bpc'.
Derek is working on a Weston implementation which uses 'link bpc' as
part of a control loop with 'max bpc' now, which should hopefully
satisfy that.

Cheers,
Daniel