On 20/03/2026 12:30, Biju Das wrote: > Hi Steven Price, > > Thanks for the feedback. > >> -----Original Message----- >> From: Steven Price <[email protected]> >> Sent: 20 March 2026 12:16 >> Subject: Re: [PATCH 3/4] drm/panfrost: Add bus_ace optional clock support >> for RZ/G2L >> >> On 04/03/2026 13:48, Biju wrote: >>> From: Biju Das <[email protected]> >>> >>> On RZ/G2L SoCs, the GPU MMU requires a bus_ace clock to operate correctly. >>> Without it, unbind/bind cycles leave the GPU non-operational, >>> manifesting as an AS_ACTIVE bit stuck and a soft reset timeout falling >>> back to hard reset. Add bus_ace_clock as an optional clock, wiring it >>> into init/fini, and the runtime suspend/resume paths alongside the >>> existing optional bus_clock. >>> >>> Signed-off-by: Biju Das <[email protected]> >>> --- >>> drivers/gpu/drm/panfrost/panfrost_device.c | 24 >>> ++++++++++++++++++++++ drivers/gpu/drm/panfrost/panfrost_device.h | >>> 1 + >>> 2 files changed, 25 insertions(+) >>> >>> diff --git a/drivers/gpu/drm/panfrost/panfrost_device.c >>> b/drivers/gpu/drm/panfrost/panfrost_device.c >>> index 01e702a0b2f0..87dae0ed748a 100644 >>> --- a/drivers/gpu/drm/panfrost/panfrost_device.c >>> +++ b/drivers/gpu/drm/panfrost/panfrost_device.c >>> @@ -70,8 +70,23 @@ static int panfrost_clk_init(struct panfrost_device >>> *pfdev) >>> goto disable_clock; >>> } >>> >>> + pfdev->bus_ace_clock = devm_clk_get_optional(pfdev->base.dev, >>> "bus_ace"); >>> + if (IS_ERR(pfdev->bus_ace_clock)) { >>> + err = PTR_ERR(pfdev->bus_ace_clock); >>> + dev_err(pfdev->base.dev, "get bus_ace_clock failed %ld\n", >>> + PTR_ERR(pfdev->bus_ace_clock)); >>> + err = PTR_ERR(pfdev->bus_ace_clock); >> >> You've assigned err twice (with the same value), and you can simplify the >> dev_err() line by using err > > Oops, forgot to take out the bottom assignment. > >> rather than the same PTR_ERR() expression again. > > I get a warning, if I use "err" in dev_err() > > panfrost_device.c:76:42: warning: format ‘%ld’ expects argument of type ‘long > int’, but argument 3 has type ‘int’ [-Wformat=] > 76 | dev_err(pfdev->base.dev, "get bus_ace_clock failed > %ld\n",
You can simply change the format string to "%d". Explanation: PTR_ERR returns a long (which matches the kernel's idea that a long is the same size as a pointer). But the standard return code size is int. So technically the assignment to err is truncating the type. However, the IS_ERR() check uses MAX_ERRNO which is 4095 so all error values will fit in an int. So we know the assignment into 'int' isn't going to truncate. [ Also it's just an error message... ;) ] Thanks, Steve > > Cheers, > Biju > >> >> With that fixed: >> >> Reviewed-by: Steven Price <[email protected]> >> >> Thanks, >> Steve >> >>> + goto disable_bus_clock; >>> + } >>> + >>> + err = clk_prepare_enable(pfdev->bus_ace_clock); >>> + if (err) >>> + goto disable_bus_clock; >>> + >>> return 0; >>> >>> +disable_bus_clock: >>> + clk_disable_unprepare(pfdev->bus_clock); >>> disable_clock: >>> clk_disable_unprepare(pfdev->clock); >>> >>> @@ -80,6 +95,7 @@ static int panfrost_clk_init(struct panfrost_device >>> *pfdev) >>> >>> static void panfrost_clk_fini(struct panfrost_device *pfdev) { >>> + clk_disable_unprepare(pfdev->bus_ace_clock); >>> clk_disable_unprepare(pfdev->bus_clock); >>> clk_disable_unprepare(pfdev->clock); >>> } >>> @@ -432,6 +448,10 @@ static int panfrost_device_runtime_resume(struct >>> device *dev) >>> ret = clk_enable(pfdev->bus_clock); >>> if (ret) >>> goto err_bus_clk; >>> + >>> + ret = clk_enable(pfdev->bus_ace_clock); >>> + if (ret) >>> + goto err_bus_ace_clk; >>> } >>> >>> panfrost_device_reset(pfdev, true); >>> @@ -439,6 +459,9 @@ static int panfrost_device_runtime_resume(struct >>> device *dev) >>> >>> return 0; >>> >>> +err_bus_ace_clk: >>> + if (pfdev->comp->pm_features & BIT(GPU_PM_RT)) >>> + clk_disable(pfdev->bus_clock); >>> err_bus_clk: >>> if (pfdev->comp->pm_features & BIT(GPU_PM_RT)) >>> clk_disable(pfdev->clock); >>> @@ -462,6 +485,7 @@ static int panfrost_device_runtime_suspend(struct >>> device *dev) >>> panfrost_gpu_power_off(pfdev); >>> >>> if (pfdev->comp->pm_features & BIT(GPU_PM_RT)) { >>> + clk_disable(pfdev->bus_ace_clock); >>> clk_disable(pfdev->bus_clock); >>> clk_disable(pfdev->clock); >>> reset_control_assert(pfdev->rstc); >>> diff --git a/drivers/gpu/drm/panfrost/panfrost_device.h >>> b/drivers/gpu/drm/panfrost/panfrost_device.h >>> index 0f3992412205..ec55c136b1b6 100644 >>> --- a/drivers/gpu/drm/panfrost/panfrost_device.h >>> +++ b/drivers/gpu/drm/panfrost/panfrost_device.h >>> @@ -136,6 +136,7 @@ struct panfrost_device { >>> void __iomem *iomem; >>> struct clk *clock; >>> struct clk *bus_clock; >>> + struct clk *bus_ace_clock; >>> struct regulator_bulk_data *regulators; >>> struct reset_control *rstc; >>> /* pm_domains for devices with more than one. */ >
