Re: [PATCH 3/4] drm/panfrost: Add bus_ace optional clock support for RZ/G2L

[Steven Price <steven.price@arm.com>]

On 04/03/2026 13:48, Biju wrote:
> From: Biju Das <biju.das.jz@bp.renesas.com>
> 
> 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 <biju.das.jz@bp.renesas.com>
> ---
>  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 rather than the same PTR_ERR()
expression again.

With that fixed:

Reviewed-by: Steven Price <steven.price@arm.com>

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. */