> -----Original Message-----
> From: dri-devel <[email protected]> On Behalf Of Adrián
> Larumbe
> Sent: 20 March 2026 21:20
> To: biju.das.au <[email protected]>
> Cc: Boris Brezillon <[email protected]>; Rob Herring
> <[email protected]>; Steven Price
> <[email protected]>; Maarten Lankhorst
> <[email protected]>; Maxime Ripard
> <[email protected]>; Thomas Zimmermann <[email protected]>; David Airlie
> <[email protected]>;
> Simona Vetter <[email protected]>; Biju Das <[email protected]>; dri-
> [email protected]; [email protected]; Geert Uytterhoeven
> <[email protected]>; Prabhakar Mahadev Lad
> <[email protected]>; linux-
> [email protected]
> Subject: Re: [PATCH v2 2/4] drm/panfrost: Drop redundant optional clock
> checks in runtime PM
>
> Hi Biju,
>
> On 20.03.2026 16:41, Biju wrote:
> > From: Biju Das <[email protected]>
> >
> > The clk_enable() and clk_disable() APIs already handle NULL clock
> > pointers gracefully — clk_enable() returns 0 and clk_disable() returns
> > immediately when passed a NULL or optional clock. The explicit if
> > (pfdev->bus_clock) guards around these calls in the runtime
> > suspend/resume paths are therefore unnecessary. Remove them to simplify the
> > code.
> >
> > Reviewed-by: Steven Price <[email protected]>
> > Signed-off-by: Biju Das <[email protected]>
> > ---
> > v1->v2:
> > * Collected tag
> > ---
> > drivers/gpu/drm/panfrost/panfrost_device.c | 12 ++++--------
> > 1 file changed, 4 insertions(+), 8 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/panfrost/panfrost_device.c
> > b/drivers/gpu/drm/panfrost/panfrost_device.c
> > index dedc13e56631..01e702a0b2f0 100644
> > --- a/drivers/gpu/drm/panfrost/panfrost_device.c
> > +++ b/drivers/gpu/drm/panfrost/panfrost_device.c
> > @@ -429,11 +429,9 @@ static int panfrost_device_runtime_resume(struct
> > device *dev)
> > if (ret)
> > goto err_clk;
> >
> > - if (pfdev->bus_clock) {
> > - ret = clk_enable(pfdev->bus_clock);
> > - if (ret)
> > - goto err_bus_clk;
> > - }
> > + ret = clk_enable(pfdev->bus_clock);
> > + if (ret)
> > + goto err_bus_clk;
> > }
>
> It seems clk_prepare_enable() can also deal with NULL clock device pointers
> gracefully, so maybe you
> could also do away with pointer checks in panfrost_clk_init?
This is the only check and no need to print rate for optional clk. That is the
reason I have not
touched this.
if (pfdev->bus_clock) {
rate = clk_get_rate(pfdev->bus_clock);
dev_info(pfdev->base.dev, "bus_clock rate = %lu\n", rate);
err = clk_prepare_enable(pfdev->bus_clock);
if (err)
goto disable_clock;
}
Cheers,
Biju
>
> Other than that,
>
> Reviewed-by: Adrián Larumbe <[email protected]>
>
> > panfrost_device_reset(pfdev, true);
> > @@ -464,9 +462,7 @@ static int panfrost_device_runtime_suspend(struct
> > device *dev)
> > panfrost_gpu_power_off(pfdev);
> >
> > if (pfdev->comp->pm_features & BIT(GPU_PM_RT)) {
> > - if (pfdev->bus_clock)
> > - clk_disable(pfdev->bus_clock);
> > -
> > + clk_disable(pfdev->bus_clock);
> > clk_disable(pfdev->clock);
> > reset_control_assert(pfdev->rstc);
> > }
> > --
> > 2.43.0
>
>
> Adrian Larumbe
