Re: [PATCH] drm: verisilicon: support non-coherent DMA framebuffers

[Dominique Belhachemi]

On Wed, May 6, 2026 at 1:14 PM Icenowy Zheng <zhengxingda@xxxxxxxxxxx> wrote:
>
> 在 2026-05-05二的 18:25 -0400，Dominique Belhachemi写道：
> > On Tue, May 5, 2026 at 5:03 AM Icenowy Zheng
> > <zhengxingda@xxxxxxxxxxx> wrote:
> > >
> > > 在 2026-05-05二的 04:26 +0000，Dominique Belhachemi写道：
> > > > Wire up the standard non-coherent path matching the ingenic DRM
> > > > driver.
> > > >
> > > > Tested on StarFive JH7110 (VisionFive 2 v1.3B).
> > >
> > > Interesting, I am curious about other patches added to test this.
> > >
> > Hi,
> >
> > I tested this on Debian unstable with a slightly patched 7.0.3 kernel
> > [1].
> > The test branch contains your verisilicon series, Michal's JH7110
> > display series [2],
> > and a JH7110 ccache change [3], which was also required to
> > communicate
> > with the BXE-4-32 firmware [4].
>
> BTW did you run any rendering? I think the way currently powervr open
> source driver works requires "coherent memory" (although it's usually
> implemented as uncached memory).

Yes, GPU dispatches run with [4].
Compute shaders run fine, but rendering crashes after a few frames.

> >
> > This change here is only used to remove the ugly framebuffer stripes
> > on the console and in the desktop environment.
>
> But I still think it'd be better to implement proper uncached memory
> support instead of flushing caches with dirty tracking.

Maybe, this patch is just a working alternative.

Dominique

> >
> > [1] https://github.com/domibel/linux/tree/jh7110_dc8200_hdmi_v7.0.3
> > [2]
> > https://lore.kernel.org/lkml/20251108-jh7110-clean-send-v1-0-06bf43bb76b1@xxxxxxxxxxx/
> > [3]
> > https://lore.kernel.org/lkml/20260430035259.3402954-1-domibel@xxxxxxxxxx/
> > [4]
> > https://github.com/domibel/linux/tree/powervr_on_jh7110_visionfive2_v7.0.3
>
> The POW_RASCALDUST thing looks quite interesting, maybe I should
> investigate it further.
>
> Thanks,
> Icenowy
> >
> > Dominique
>
>