RE: [PATCH 1/2] dmaengine: qcom-bam-dma: Add pm_runtime support

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Hi,

> -----Original Message-----
> From: dmaengine-owner@xxxxxxxxxxxxxxx [mailto:dmaengine-
> owner@xxxxxxxxxxxxxxx] On Behalf Of Pramod Gurav
> Sent: Monday, May 02, 2016 5:48 PM
> To: vinod.koul@xxxxxxxxx; andy.gross@xxxxxxxxxx; ulf.hansson@xxxxxxxxxx;
> rjw@xxxxxxxxxxxxx; linux-arm-msm@xxxxxxxxxxxxxxx
> Cc: linux-pm@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
> dmaengine@xxxxxxxxxxxxxxx; stanimir.varbanov@xxxxxxxxxx;
> okaya@xxxxxxxxxxxxxx; Pramod Gurav <pramod.gurav@xxxxxxxxxx>
> Subject: [PATCH 1/2] dmaengine: qcom-bam-dma: Add pm_runtime support
> 
> Adds pm_runtime support for BAM DMA so that clock
> is enabled only when there is a transaction going on to help
> save power.
> 
> Signed-off-by: Pramod Gurav <pramod.gurav@xxxxxxxxxx>
> ---
>  drivers/dma/qcom/bam_dma.c | 88
> +++++++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 87 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/dma/qcom/bam_dma.c b/drivers/dma/qcom/bam_dma.c
> index 5b427c4..577f323 100644
> --- a/drivers/dma/qcom/bam_dma.c
> +++ b/drivers/dma/qcom/bam_dma.c
> @@ -48,6 +48,7 @@
>  #include <linux/of_dma.h>
>  #include <linux/clk.h>
>  #include <linux/dmaengine.h>
> +#include <linux/pm_runtime.h>
> 
>  #include "../dmaengine.h"
>  #include "../virt-dma.h"
> @@ -58,6 +59,8 @@ struct bam_desc_hw {
>  	u16 flags;
>  };
> 
> +#define BAM_DMA_AUTOSUSPEND_DELAY 100
> +
>  #define DESC_FLAG_INT BIT(15)
>  #define DESC_FLAG_EOT BIT(14)
>  #define DESC_FLAG_EOB BIT(13)
> @@ -535,6 +538,7 @@ static void bam_free_chan(struct dma_chan *chan)
>  		return;
>  	}
> 
> +	pm_runtime_get_sync(bdev->dev);
>  	spin_lock_irqsave(&bchan->vc.lock, flags);
>  	bam_reset_channel(bchan);
>  	spin_unlock_irqrestore(&bchan->vc.lock, flags);
> @@ -550,6 +554,8 @@ static void bam_free_chan(struct dma_chan *chan)
> 
>  	/* disable irq */
>  	writel_relaxed(0, bam_addr(bdev, bchan->id, BAM_P_IRQ_EN));
> +	pm_runtime_mark_last_busy(bdev->dev);
> +	pm_runtime_put_autosuspend(bdev->dev);
>  }
> 
>  /**
> @@ -696,10 +702,13 @@ static int bam_pause(struct dma_chan *chan)
>  	struct bam_device *bdev = bchan->bdev;
>  	unsigned long flag;
> 
> +	pm_runtime_get_sync(bdev->dev);
>  	spin_lock_irqsave(&bchan->vc.lock, flag);
>  	writel_relaxed(1, bam_addr(bdev, bchan->id, BAM_P_HALT));
>  	bchan->paused = 1;
>  	spin_unlock_irqrestore(&bchan->vc.lock, flag);
> +	pm_runtime_mark_last_busy(bdev->dev);
> +	pm_runtime_put_autosuspend(bdev->dev);
> 
>  	return 0;
>  }
> @@ -715,10 +724,13 @@ static int bam_resume(struct dma_chan *chan)
>  	struct bam_device *bdev = bchan->bdev;
>  	unsigned long flag;
> 
> +	pm_runtime_get_sync(bdev->dev);
>  	spin_lock_irqsave(&bchan->vc.lock, flag);
>  	writel_relaxed(0, bam_addr(bdev, bchan->id, BAM_P_HALT));
>  	bchan->paused = 0;
>  	spin_unlock_irqrestore(&bchan->vc.lock, flag);
> +	pm_runtime_mark_last_busy(bdev->dev);
> +	pm_runtime_put_autosuspend(bdev->dev);
> 
>  	return 0;
>  }
> @@ -943,6 +955,7 @@ static void bam_start_dma(struct bam_chan *bchan)
>  	wmb();
>  	writel_relaxed(bchan->tail * sizeof(struct bam_desc_hw),
>  			bam_addr(bdev, bchan->id, BAM_P_EVNT_REG));
> +

Unrelated change...

>  }
> 
>  /**
> @@ -967,6 +980,9 @@ static void dma_tasklet(unsigned long data)
>  			bam_start_dma(bchan);
>  		spin_unlock_irqrestore(&bchan->vc.lock, flags);
>  	}
> +
> +	pm_runtime_mark_last_busy(bdev->dev);
> +	pm_runtime_put_autosuspend(bdev->dev);
>  }
> 
>  /**
> @@ -978,8 +994,12 @@ static void dma_tasklet(unsigned long data)
>  static void bam_issue_pending(struct dma_chan *chan)
>  {
>  	struct bam_chan *bchan = to_bam_chan(chan);
> +	struct bam_device *bdev = bchan->bdev;
>  	unsigned long flags;
> 
> +	if (pm_runtime_status_suspended(bdev->dev))
> +		pm_runtime_get_sync(bdev->dev);
> +
>  	spin_lock_irqsave(&bchan->vc.lock, flags);
> 
>  	/* if work pending and idle, start a transaction */
> @@ -1210,6 +1230,13 @@ static int bam_dma_probe(struct platform_device
> *pdev)
>  	if (ret)
>  		goto err_unregister_dma;
> 
> +	pm_runtime_irq_safe(&pdev->dev);
> +	pm_runtime_set_autosuspend_delay(&pdev->dev,
> BAM_DMA_AUTOSUSPEND_DELAY);
> +	pm_runtime_use_autosuspend(&pdev->dev);
> +	pm_runtime_mark_last_busy(&pdev->dev);
> +	pm_runtime_set_active(&pdev->dev);
> +	pm_runtime_enable(&pdev->dev);
> +
>  	return 0;
> 
>  err_unregister_dma:
> @@ -1221,7 +1248,6 @@ err_tasklet_kill:
>  	tasklet_kill(&bdev->task);
>  err_disable_clk:
>  	clk_disable_unprepare(bdev->bamclk);
> -

Unrelated change....

>  	return ret;
>  }
> 
> @@ -1252,16 +1278,76 @@ static int bam_dma_remove(struct
> platform_device *pdev)
> 
>  	tasklet_kill(&bdev->task);
> 
> +	pm_runtime_get_sync(&pdev->dev);
>  	clk_disable_unprepare(bdev->bamclk);
> +	pm_runtime_disable(&pdev->dev);
> +	pm_runtime_put_noidle(&pdev->dev);
> +	pm_runtime_set_suspended(&pdev->dev);
> +
> +	return 0;
> +}
> +
> +static int bam_dma_runtime_suspend(struct device *dev)
> +{
> +	struct bam_device *bdev = dev_get_drvdata(dev);
> +
> +	clk_disable(bdev->bamclk);
> +
> +	return 0;
> +}
> +
> +static int bam_dma_runtime_resume(struct device *dev)
> +{
> +	struct bam_device *bdev = dev_get_drvdata(dev);
> +	int ret;
> +
> +	ret = clk_enable(bdev->bamclk);

Instead of clk_enable why can't you call the clk_prepare_enable directly here?
clk_disable_unprepare in the suspend.

I mean in the probe remove the clk_prepare_enable and wherever you need to access the
Device register call the pm_runtime_get_sync.

Thanks,
Kedar.

> +	if (ret < 0) {
> +		dev_err(dev, "clk_enable failed: %d\n", ret);
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +#ifdef CONFIG_PM_SLEEP
> +static int bam_dma_suspend(struct device *dev)
> +{
> +	struct bam_device *bdev = dev_get_drvdata(dev);
> +
> +	pm_runtime_force_suspend(dev);
> +
> +	clk_unprepare(bdev->bamclk);
> +
> +	return 0;
> +}
> +
> +static int bam_dma_resume(struct device *dev)
> +{
> +	struct bam_device *bdev = dev_get_drvdata(dev);
> +	int ret;
> +
> +	ret = clk_prepare(bdev->bamclk);
> +	if (ret)
> +		return ret;
> +
> +	pm_runtime_force_resume(dev);
> 
>  	return 0;
>  }
> +#endif
> +
> +static const struct dev_pm_ops bam_dma_pm_ops = {
> +	SET_LATE_SYSTEM_SLEEP_PM_OPS(bam_dma_suspend,
> bam_dma_resume)
> +	SET_RUNTIME_PM_OPS(bam_dma_runtime_suspend,
> bam_dma_runtime_resume,
> +				NULL)
> +};
> 
>  static struct platform_driver bam_dma_driver = {
>  	.probe = bam_dma_probe,
>  	.remove = bam_dma_remove,
>  	.driver = {
>  		.name = "bam-dma-engine",
> +		.pm = &bam_dma_pm_ops,
>  		.of_match_table = bam_of_match,
>  	},
>  };
> --
> 1.8.2.1
> 
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