linux-kernel - Re: [PATCH v3] drm/v3d/v3d_drv: Fix PM disable depth imbalance

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Message-ID: <YpdpCWW9+igsVydr@phenom.ffwll.local>
Date:   Wed, 1 Jun 2022 15:26:33 +0200
From:   Daniel Vetter <daniel@...ll.ch>
To:     Miaoqian Lin <linmq006@...il.com>
Cc:     Emma Anholt <emma@...olt.net>, David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>, Eric Anholt <eric@...olt.net>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] drm/v3d/v3d_drv: Fix PM disable depth imbalance

On Wed, Jun 01, 2022 at 04:20:50PM +0400, Miaoqian Lin wrote:
> The pm_runtime_enable will increase power disable depth.
> If the probe fails, we should use pm_runtime_disable() to balance
> pm_runtime_enable().
> Also call disable function in remove function.
> 
> Fixes: 57692c94dcbe ("drm/v3d: Introduce a new DRM driver for Broadcom V3D V3.x+")
> Signed-off-by: Miaoqian Lin <linmq006@...il.com>
> ---
> Changes in v3:
> - call pm_runtime_disable() in v3d_platform_drm_remove
> - update commit message
> 
> Changes in v2
> - put pm_runtime_disable before dma_free_wc
> - rename dma_free to pm_disable
> 
> v1: https://lore.kernel.org/r/20220105120442.14418-1-linmq006@gmail.com
> v2: https://lore.kernel.org/r/20220106124657.32737-1-linmq006@gmail.com

Maybe a bit late since we're at v3 already, but are there no devm_
functions here that would dtrt automatically? Or is there another reason
we can't use them?
-Daniel
> ---
>  drivers/gpu/drm/v3d/v3d_drv.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/v3d/v3d_drv.c b/drivers/gpu/drm/v3d/v3d_drv.c
> index 1afcd54fbbd5..f3380399fe17 100644
> --- a/drivers/gpu/drm/v3d/v3d_drv.c
> +++ b/drivers/gpu/drm/v3d/v3d_drv.c
> @@ -286,7 +286,7 @@ static int v3d_platform_drm_probe(struct platform_device *pdev)
>  
>  	ret = v3d_gem_init(drm);
>  	if (ret)
> -		goto dma_free;
> +		goto pm_disable;
>  
>  	ret = v3d_irq_init(v3d);
>  	if (ret)
> @@ -302,7 +302,8 @@ static int v3d_platform_drm_probe(struct platform_device *pdev)
>  	v3d_irq_disable(v3d);
>  gem_destroy:
>  	v3d_gem_destroy(drm);
> -dma_free:
> +pm_disable:
> +	pm_runtime_disable(dev);
>  	dma_free_wc(dev, 4096, v3d->mmu_scratch, v3d->mmu_scratch_paddr);
>  	return ret;
>  }
> @@ -316,6 +317,7 @@ static int v3d_platform_drm_remove(struct platform_device *pdev)
>  
>  	v3d_gem_destroy(drm);
>  
> +	pm_runtime_disable(&pdev->dev);
>  	dma_free_wc(v3d->drm.dev, 4096, v3d->mmu_scratch,
>  		    v3d->mmu_scratch_paddr);
>  
> -- 
> 2.25.1
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch