linux-kernel - Re: [PATCH v1] dmaengine: fsl-edma: add runtime suspend/resume support

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Message-ID: <Z2p/CLHFqdamp4Bq@vaman>
Date: Tue, 24 Dec 2024 14:59:44 +0530
From: Vinod Koul <vkoul@...nel.org>
To: Joy Zou <joy.zou@....com>
Cc: frank.li@....com, shengjiu.wang@....com, imx@...ts.linux.dev,
	dmaengine@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1] dmaengine: fsl-edma: add runtime suspend/resume
 support

On 20-12-24, 10:11, Joy Zou wrote:
> Introduce runtime suspend and resume support for FSL eDMA. Enable
> per-channel power domain management to facilitate runtime suspend and
> resume operations.
> 
> Implement runtime suspend and resume functions for the eDMA engine and
> individual channels.
> 
> Link per-channel power domain device to eDMA per-channel device instead of
> eDMA engine device. So Power Manage framework manage power state of linked
> domain device when per-channel device request runtime resume/suspend.
> 
> Trigger the eDMA engine's runtime suspend when all channels are suspended,
> disabling all common clocks through the runtime PM framework.
> 
> Signed-off-by: Joy Zou <joy.zou@....com>
> Signed-off-by: Frank Li <Frank.Li@....com>
> ---
>  drivers/dma/fsl-edma-common.c |  15 ++---
>  drivers/dma/fsl-edma-main.c   | 115 ++++++++++++++++++++++++++++++----
>  2 files changed, 110 insertions(+), 20 deletions(-)
> 
> diff --git a/drivers/dma/fsl-edma-common.c b/drivers/dma/fsl-edma-common.c
> index b7f15ab96855..fcdb53b21f38 100644
> --- a/drivers/dma/fsl-edma-common.c
> +++ b/drivers/dma/fsl-edma-common.c
> @@ -243,9 +243,6 @@ int fsl_edma_terminate_all(struct dma_chan *chan)
>  	spin_unlock_irqrestore(&fsl_chan->vchan.lock, flags);
>  	vchan_dma_desc_free_list(&fsl_chan->vchan, &head);
>  
> -	if (fsl_edma_drvflags(fsl_chan) & FSL_EDMA_DRV_HAS_PD)
> -		pm_runtime_allow(fsl_chan->pd_dev);
> -
>  	return 0;
>  }
>  
> @@ -805,8 +802,12 @@ int fsl_edma_alloc_chan_resources(struct dma_chan *chan)
>  	struct fsl_edma_chan *fsl_chan = to_fsl_edma_chan(chan);
>  	int ret;
>  
> -	if (fsl_edma_drvflags(fsl_chan) & FSL_EDMA_DRV_HAS_CHCLK)
> -		clk_prepare_enable(fsl_chan->clk);
> +	ret = pm_runtime_get_sync(&fsl_chan->vchan.chan.dev->device);
> +	if (ret < 0) {
> +		dev_err(&fsl_chan->vchan.chan.dev->device, "pm_runtime_get_sync() failed\n");
> +		pm_runtime_disable(&fsl_chan->vchan.chan.dev->device);
> +		return ret;
> +	}
>  
>  	fsl_chan->tcd_pool = dma_pool_create("tcd_pool", chan->device->dev,
>  				fsl_edma_drvflags(fsl_chan) & FSL_EDMA_DRV_TCD64 ?
> @@ -819,6 +820,7 @@ int fsl_edma_alloc_chan_resources(struct dma_chan *chan)
>  
>  		if (ret) {
>  			dma_pool_destroy(fsl_chan->tcd_pool);
> +			pm_runtime_put_sync_suspend(&fsl_chan->vchan.chan.dev->device);
>  			return ret;
>  		}
>  	}
> @@ -851,8 +853,7 @@ void fsl_edma_free_chan_resources(struct dma_chan *chan)
>  	fsl_chan->is_sw = false;
>  	fsl_chan->srcid = 0;
>  	fsl_chan->is_remote = false;
> -	if (fsl_edma_drvflags(fsl_chan) & FSL_EDMA_DRV_HAS_CHCLK)
> -		clk_disable_unprepare(fsl_chan->clk);
> +	pm_runtime_put_sync_suspend(&fsl_chan->vchan.chan.dev->device);
>  }
>  
>  void fsl_edma_cleanup_vchan(struct dma_device *dmadev)
> diff --git a/drivers/dma/fsl-edma-main.c b/drivers/dma/fsl-edma-main.c
> index 60de1003193a..75d6c8984c8e 100644
> --- a/drivers/dma/fsl-edma-main.c
> +++ b/drivers/dma/fsl-edma-main.c
> @@ -420,7 +420,6 @@ MODULE_DEVICE_TABLE(of, fsl_edma_dt_ids);
>  static int fsl_edma3_attach_pd(struct platform_device *pdev, struct fsl_edma_engine *fsl_edma)
>  {
>  	struct fsl_edma_chan *fsl_chan;
> -	struct device_link *link;
>  	struct device *pd_chan;
>  	struct device *dev;
>  	int i;
> @@ -439,24 +438,39 @@ static int fsl_edma3_attach_pd(struct platform_device *pdev, struct fsl_edma_eng
>  			return -EINVAL;
>  		}
>  
> -		link = device_link_add(dev, pd_chan, DL_FLAG_STATELESS |
> -					     DL_FLAG_PM_RUNTIME |
> -					     DL_FLAG_RPM_ACTIVE);
> -		if (!link) {
> -			dev_err(dev, "Failed to add device_link to %d\n", i);
> -			return -EINVAL;
> -		}
> -
>  		fsl_chan->pd_dev = pd_chan;
> -
> -		pm_runtime_use_autosuspend(fsl_chan->pd_dev);
> -		pm_runtime_set_autosuspend_delay(fsl_chan->pd_dev, 200);
> -		pm_runtime_set_active(fsl_chan->pd_dev);
>  	}
>  
>  	return 0;
>  }
>  
> +/* Per channel dma power domain */
> +static int fsl_edma_chan_runtime_suspend(struct device *dev)
> +{
> +	struct fsl_edma_chan *fsl_chan = dev_get_drvdata(dev);
> +	int ret = 0;
> +
> +	clk_disable_unprepare(fsl_chan->clk);
> +
> +	return ret;

Unused ret! drop it

> +}
> +
> +static int fsl_edma_chan_runtime_resume(struct device *dev)
> +{
> +	struct fsl_edma_chan *fsl_chan = dev_get_drvdata(dev);
> +	int ret;
> +
> +	ret = clk_prepare_enable(fsl_chan->clk);
> +
> +	return ret;

how about return clk_prepare_enable()

-- 
~Vinod