Re: [PATCH 1/2] drm/arm/malidp: fix ignored clk_prepare_enable() in runtime PM resume

[Liviu Dudau <liviu.dudau@arm.com>]

On Sun, May 31, 2026 at 05:29:57AM +0000, Gustavo Kenji Mendonça Kaneko wrote:
> malidp_runtime_pm_resume() calls clk_prepare_enable() three times
> without checking the return value. If any clock fails to enable, the
> driver silently proceeds with unclocked hardware, leading to undefined
> behavior.
> 
> Use clk_bulk_prepare_enable() which atomically enables all clocks and
> automatically rolls back successfully enabled clocks on failure. This
> is consistent with how the suspend path already uses
> clk_bulk_disable_unprepare() in malidp_runtime_pm_suspend().
> 
> This issue was found by code review without access to Mali DP hardware.
> 
> Signed-off-by: Gustavo Kenji Mendonça Kaneko <kaneko.dev@pm.me>

Reviewed-by: Liviu Dudau <liviu.dudau@arm.com>

Best regards,
Liviu

> ---
>  drivers/gpu/drm/arm/malidp_drv.c | 13 ++++++++++---
>  1 file changed, 10 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/arm/malidp_drv.c b/drivers/gpu/drm/arm/malidp_drv.c
> index b765f6c9eea4..1e4336c3a2fa 100644
> --- a/drivers/gpu/drm/arm/malidp_drv.c
> +++ b/drivers/gpu/drm/arm/malidp_drv.c
> @@ -689,10 +689,17 @@ static int malidp_runtime_pm_resume(struct device *dev)
>  	struct drm_device *drm = dev_get_drvdata(dev);
>  	struct malidp_drm *malidp = drm_to_malidp(drm);
>  	struct malidp_hw_device *hwdev = malidp->dev;
> +	struct clk_bulk_data clks[] = {
> +		{ .clk = hwdev->pclk },
> +		{ .clk = hwdev->aclk },
> +		{ .clk = hwdev->mclk },
> +	};
> +	int err;
> +
> +	err = clk_bulk_prepare_enable(ARRAY_SIZE(clks), clks);
> +	if (err)
> +		return err;
>  
> -	clk_prepare_enable(hwdev->pclk);
> -	clk_prepare_enable(hwdev->aclk);
> -	clk_prepare_enable(hwdev->mclk);
>  	hwdev->pm_suspended = false;
>  	malidp_de_irq_hw_init(hwdev);
>  	malidp_se_irq_hw_init(hwdev);
> -- 
> 2.54.0
> 
> 

-- 
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