Re: [PATCH 3/5] drm/rcar-du: dsc: Add rudimentary Renesas R-Car V4H DSC driver

[Tomi Valkeinen]

Hi Geert,

On 15/05/2026 10:49, Geert Uytterhoeven wrote:
> Hi Tomi,
>
> On Thu, 14 May 2026 at 14:25, Tomi Valkeinen
> <tomi.valkeinen+renesas@xxxxxxxxxxxxxxxx> wrote:
> > From: Marek Vasut <marek.vasut+renesas@xxxxxxxxxxx>
> >
> > The Renesas DSC Display Stream Compression is a bridge embedded in the
> > Renesas R-Car V4H SoC. The bridge performs VESA DSC encoding of up to
> > 8k or 400 Mpixel/s . Add rudimentary driver, which currently acts as a
> > pass-through bridge and allows DSI1 to be operational on R-Car V4H.
> >
> > Signed-off-by: Marek Vasut <marek.vasut+renesas@xxxxxxxxxxx>
> > [tomi.valkeinen: use bridge->next_bridge, minor changes]
> > Signed-off-by: Tomi Valkeinen <tomi.valkeinen+renesas@xxxxxxxxxxxxxxxx>
>
> Thanks for your patch!
>
> > --- /dev/null
> > +++ b/drivers/gpu/drm/renesas/rcar-du/rcar_dsc.c
>
> > +
> > +static void rcar_dsc_atomic_enable(struct drm_bridge *bridge,
> > +                                  struct drm_atomic_state *state)
> > +{
> > +       struct rcar_dsc *dsc = bridge_to_rcar_dsc(bridge);
> > +
> > +       WARN_ON(clk_prepare_enable(dsc->clk));

Ah, just missed your comment and sent the v2.

> Who don't you use pm_runtime_resume_and_get() instead, like
> rcar_cmm.c? Then you don't need to get the clock at all, and the driver

Hmm, why wouldn't I need to get the clock? What does the runtime PM do 
on Renesas?

> will keep on working if the DSC ever ends up in a power domain.
I can add runtime PM. I just felt that it was overcomplicating a "dummy" 
driver that just needs to enable the clock when the video pipeline is 
enabled.

 Tomi