drm/amd/display: disable display DCC with retiling due to worse power consumption

[Marek Olšák]

On Fri, Apr 28, 2023, 16:14 Joshua Ashton <joshua at froggi.es> wrote:

> I mean I would also like power and perf numbers for Vangogh given you
> referenced 10.3.
>
> Generic "power consumption is better" isn't enough to convince me that
> this is the right call.
>

Raphael and Mendocino have worse power consumption with retiled displayable
DCC and modifiers, and that can also be due to how retiling is implemented
for modifiers.

Marek


> - Joshie 🐸✨
>
> On Friday, 28 April 2023, Marek Olšák <maraeo at gmail.com> wrote:
> > I thought the same thing initially, but then realized that's not how
> modifiers were designed to work.
> > Mesa should expose all modifiers it wants to allow for 3D and it doesn't
> care which ones are displayable.
> > The kernel should expose all modifiers it wants to allow for display.
> > With that, Mesa can still use theoretically displayable DCC, but it will
> only be used for anything that's not the display.
> > We can, of course, disable it in Mesa instead to get the same effect.
> > We would need perf numbers for dGPUs to be able to tell whether it's
> beneficial with the cost of DCC retiling.
> > Marek
> >
> > On Fri, Apr 28, 2023, 12:11 Joshua Ashton <joshua at froggi.es> wrote:
> >>
> >> I really don't think the kernel isn't the right place to do this.
> >> Is there any reason to not just disable it from the Mesa side?
> >>
> >> We can already disable displayable DCC there, so I don't see why you
> are even touching the kernel.
> >> It makes it infinitely harder for anyone to evaluate perf and power
> tradeoffs if you disable it at this level.
> >>
> >> The whole power vs perf trade is also not a big deal on dGPUs compared
> to APUs. Probably needs a better heuristic either way to avoid regressing
> perf.
> >>
> >> - Joshie 🐸✨
> >>
> >> On 28 April 2023 10:47:17 BST, "Marek Olšák" <maraeo at gmail.com> wrote:
> >>>
> >>> Hi,
> >>> It's attached for review.
> >>>
> >>> Thanks,
> >>> Marek
> >
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