linux-kernel - Re: [PATCH] dmaengine: qcom: bam

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Date:   Thu, 16 Jun 2022 07:00:15 -0700
From:   Vinod Koul <vkoul@...nel.org>
To:     Caleb Connolly <caleb.connolly@...aro.org>
Cc:     Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
        linux-arm-msm@...r.kernel.org, dmaengine@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] dmaengine: qcom: bam_dma: fix runtime PM underflow

On 09-06-22, 20:50, Caleb Connolly wrote:
> When PM runtime is disabled, pm_runtime_get() isn't called, but
> pm_runtime_put() still is. Fix this by creating a matching wrapper
> on pm_runtime_put_autosuspend().
> 
> Fixes: dbad41e7bb5f ("dmaengine: qcom: bam_dma: check if the runtime pm enabled")
> Signed-off-by: Caleb Connolly <caleb.connolly@...aro.org>
> ---
>  drivers/dma/qcom/bam_dma.c | 18 +++++++++++++-----
>  1 file changed, 13 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/dma/qcom/bam_dma.c b/drivers/dma/qcom/bam_dma.c
> index 87f6ca1541cf..a36dedee262e 100644
> --- a/drivers/dma/qcom/bam_dma.c
> +++ b/drivers/dma/qcom/bam_dma.c
> @@ -566,6 +566,14 @@ static int bam_pm_runtime_get_sync(struct device *dev)
>  	return 0;
>  }
>  
> +static int bam_pm_runtime_put_autosuspend(struct device *dev)
> +{
> +	if (pm_runtime_enabled(dev))
> +		return pm_runtime_put_autosuspend(dev);
> +
> +	return 0;
> +}

should we really do a wrapper to fix this ;-) I would think dropping the
get wrapper and calling pm_runtime_get() unconditionally would be
better..?

> +
>  /**
>   * bam_free_chan - Frees dma resources associated with specific channel
>   * @chan: specified channel
> @@ -617,7 +625,7 @@ static void bam_free_chan(struct dma_chan *chan)
>  
>  err:
>  	pm_runtime_mark_last_busy(bdev->dev);
> -	pm_runtime_put_autosuspend(bdev->dev);
> +	bam_pm_runtime_put_autosuspend(bdev->dev);
>  }
>  
>  /**
> @@ -793,7 +801,7 @@ static int bam_pause(struct dma_chan *chan)
>  	bchan->paused = 1;
>  	spin_unlock_irqrestore(&bchan->vc.lock, flag);
>  	pm_runtime_mark_last_busy(bdev->dev);
> -	pm_runtime_put_autosuspend(bdev->dev);
> +	bam_pm_runtime_put_autosuspend(bdev->dev);
>  
>  	return 0;
>  }
> @@ -819,7 +827,7 @@ static int bam_resume(struct dma_chan *chan)
>  	bchan->paused = 0;
>  	spin_unlock_irqrestore(&bchan->vc.lock, flag);
>  	pm_runtime_mark_last_busy(bdev->dev);
> -	pm_runtime_put_autosuspend(bdev->dev);
> +	bam_pm_runtime_put_autosuspend(bdev->dev);
>  
>  	return 0;
>  }
> @@ -936,7 +944,7 @@ static irqreturn_t bam_dma_irq(int irq, void *data)
>  	}
>  
>  	pm_runtime_mark_last_busy(bdev->dev);
> -	pm_runtime_put_autosuspend(bdev->dev);
> +	bam_pm_runtime_put_autosuspend(bdev->dev);
>  
>  	return IRQ_HANDLED;
>  }
> @@ -1111,7 +1119,7 @@ static void bam_start_dma(struct bam_chan *bchan)
>  			bam_addr(bdev, bchan->id, BAM_P_EVNT_REG));
>  
>  	pm_runtime_mark_last_busy(bdev->dev);
> -	pm_runtime_put_autosuspend(bdev->dev);
> +	bam_pm_runtime_put_autosuspend(bdev->dev);
>  }
>  
>  /**
> -- 
> 2.36.1

-- 
~Vinod