linux-kernel - Re: [PATCH 5/6] mtd: rawnand: gpmi: refine the runtime pm ops

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Date:   Wed, 15 Jan 2020 09:32:26 +0100
From:   Sascha Hauer <s.hauer@...gutronix.de>
To:     Han Xu <han.xu@....com>
Cc:     vkoul@...nel.org, shawnguo@...nel.org, miquel.raynal@...tlin.com,
        richard@....at, vigneshr@...com, esben@...nix.com,
        boris.brezillon@...labora.com, festevam@...il.com,
        linux-imx@....com, dmaengine@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 5/6] mtd: rawnand: gpmi: refine the runtime pm ops

On Wed, Jan 15, 2020 at 05:44:02AM +0800, Han Xu wrote:
> several changes for runtime code in gpmi-nand driver
> 
> - Always invoke runtime get/put in same function to balance the usage
> counter.
> 
> - leverage the runtime pm for system pm, move acquire dma to runtime pm
> to acquire dma only when needed.
> 
> - add pm_runtime_dont_use_autosuspend in err path. If driver failed to
> probe before runtime pm timeout, such as NAND not mounted in socket,
> runtime suspend won't be called without the change.

Using a bullet list in a commit message is often a sign that the patch
should be split into multiple patches...

> 
> Signed-off-by: Han Xu <han.xu@....com>
> ---
>  drivers/mtd/nand/raw/gpmi-nand/gpmi-nand.c | 56 +++++++++++-----------
>  1 file changed, 29 insertions(+), 27 deletions(-)
> 
> diff --git a/drivers/mtd/nand/raw/gpmi-nand/gpmi-nand.c b/drivers/mtd/nand/raw/gpmi-nand/gpmi-nand.c
> index fcc7325f2a10..73644c96fa9b 100644
> --- a/drivers/mtd/nand/raw/gpmi-nand/gpmi-nand.c
> +++ b/drivers/mtd/nand/raw/gpmi-nand/gpmi-nand.c
> @@ -183,7 +183,6 @@ static int gpmi_init(struct gpmi_nand_data *this)
>  	 */
>  	writel(BM_GPMI_CTRL1_DECOUPLE_CS, r->gpmi_regs + HW_GPMI_CTRL1_SET);
>  
> -	return 0;
>  err_out:
>  	pm_runtime_mark_last_busy(this->dev);
>  	pm_runtime_put_autosuspend(this->dev);
> @@ -556,7 +555,6 @@ static int bch_set_geometry(struct gpmi_nand_data *this)
>  	/* Set *all* chip selects to use layout 0. */
>  	writel(0, r->bch_regs + HW_BCH_LAYOUTSELECT);
>  
> -	ret = 0;
>  err_out:
>  	pm_runtime_mark_last_busy(this->dev);
>  	pm_runtime_put_autosuspend(this->dev);

While I agree that this "ret = 0" is unnecessary because 'ret' holds the
successful return value of the last function called, I still think it's
nice to make it explicit that this is the success path of this function.

If you disagree please at least make this a separate patch.

> @@ -1213,10 +1211,6 @@ static int acquire_resources(struct gpmi_nand_data *this)
>  	if (ret)
>  		goto exit_regs;
>  
> -	ret = acquire_dma_channels(this);
> -	if (ret)
> -		goto exit_regs;
> -
>  	ret = gpmi_get_clks(this);
>  	if (ret)
>  		goto exit_clock;
> @@ -2656,15 +2650,9 @@ static int gpmi_nand_probe(struct platform_device *pdev)
>  	if (ret)
>  		goto exit_acquire_resources;
>  
> -	ret = __gpmi_enable_clk(this, true);
> -	if (ret)
> -		goto exit_nfc_init;
> -
> +	pm_runtime_enable(&pdev->dev);
>  	pm_runtime_set_autosuspend_delay(&pdev->dev, 500);
>  	pm_runtime_use_autosuspend(&pdev->dev);
> -	pm_runtime_set_active(&pdev->dev);
> -	pm_runtime_enable(&pdev->dev);
> -	pm_runtime_get_sync(&pdev->dev);
>  
>  	ret = gpmi_init(this);
>  	if (ret)
> @@ -2674,15 +2662,12 @@ static int gpmi_nand_probe(struct platform_device *pdev)
>  	if (ret)
>  		goto exit_nfc_init;
>  
> -	pm_runtime_mark_last_busy(&pdev->dev);
> -	pm_runtime_put_autosuspend(&pdev->dev);
> -
>  	dev_info(this->dev, "driver registered.\n");
>  
>  	return 0;
>  
>  exit_nfc_init:
> -	pm_runtime_put(&pdev->dev);
> +	pm_runtime_dont_use_autosuspend(&pdev->dev);
>  	pm_runtime_disable(&pdev->dev);
>  	release_resources(this);
>  exit_acquire_resources:
> @@ -2694,7 +2679,6 @@ static int gpmi_nand_remove(struct platform_device *pdev)
>  {
>  	struct gpmi_nand_data *this = platform_get_drvdata(pdev);
>  
> -	pm_runtime_put_sync(&pdev->dev);
>  	pm_runtime_disable(&pdev->dev);
>  
>  	nand_release(&this->nand);
> @@ -2706,10 +2690,11 @@ static int gpmi_nand_remove(struct platform_device *pdev)
>  #ifdef CONFIG_PM_SLEEP
>  static int gpmi_pm_suspend(struct device *dev)
>  {
> -	struct gpmi_nand_data *this = dev_get_drvdata(dev);
> +	int ret;
>  
> -	release_dma_channels(this);
> -	return 0;
> +	ret = pm_runtime_force_suspend(dev);
> +
> +	return ret;
>  }
>  
>  static int gpmi_pm_resume(struct device *dev)
> @@ -2717,9 +2702,11 @@ static int gpmi_pm_resume(struct device *dev)
>  	struct gpmi_nand_data *this = dev_get_drvdata(dev);
>  	int ret;
>  
> -	ret = acquire_dma_channels(this);
> -	if (ret < 0)
> +	ret = pm_runtime_force_resume(dev);
> +	if (ret) {
> +		dev_err(this->dev, "Error in resume %d\n", ret);
>  		return ret;
> +	}
>  
>  	/* re-init the GPMI registers */
>  	ret = gpmi_init(this);
> @@ -2743,18 +2730,33 @@ static int gpmi_pm_resume(struct device *dev)
>  }
>  #endif /* CONFIG_PM_SLEEP */
>  
> -static int __maybe_unused gpmi_runtime_suspend(struct device *dev)
> +#define gpmi_enable_clk(x)	__gpmi_enable_clk(x, true)
> +#define gpmi_disable_clk(x)	__gpmi_enable_clk(x, false)

These defines do not add any value.

Sascha

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