Re: [PATCH] mtd: rawnand: gpmi: fix the suspend/resume issue

[Esben Haabendal <esben@xxxxxxxxxx>]

Hi Han

See comments/questions below.

If I understand the purpose of some of your changes correct, you are
fixing the handling of pm usage counter, as it currently is incremented
in gpmi_init() and decremented in gpmi_nand_remove().  I believe that
would be nice to have in a separate patch with an explanation of the
change.

Han Xu <han.xu@xxxxxxx> writes:

> fix several issues when system suspend/resume,
>
> - leverage the runtime pm for system suspend/resume
> - enable the clock before register access
> - re-apply timing settings
> - set the proper pinctrl state
>
> Signed-off-by: Han Xu <han.xu@xxxxxxx>
> ---
>  drivers/mtd/nand/raw/gpmi-nand/gpmi-nand.c | 59 ++++++++++++++++------
>  1 file changed, 44 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/mtd/nand/raw/gpmi-nand/gpmi-nand.c b/drivers/mtd/nand/raw/gpmi-nand/gpmi-nand.c
> index 334fe3130285..37437d47ab9a 100644
> --- a/drivers/mtd/nand/raw/gpmi-nand/gpmi-nand.c
> +++ b/drivers/mtd/nand/raw/gpmi-nand/gpmi-nand.c
> @@ -15,6 +15,7 @@
>  #include <linux/of.h>
>  #include <linux/of_device.h>
>  #include <linux/pm_runtime.h>
> +#include <linux/pinctrl/consumer.h>
>  #include <linux/dma/mxs-dma.h>
>  #include "gpmi-nand.h"
>  #include "gpmi-regs.h"
> @@ -146,7 +147,11 @@ static int __gpmi_enable_clk(struct gpmi_nand_data *this, bool v)
>  static int gpmi_init(struct gpmi_nand_data *this)
>  {
>  	struct resources *r = &this->resources;
> -	int ret;
> +	int ret = 0;

I don't see why this is changed, given that ret is unconditionally
assigned in the next line.

> +
> +	ret = pm_runtime_get_sync(this->dev);
> +	if (ret < 0)
> +		return ret;
>  
>  	ret = gpmi_reset_block(r->gpmi_regs, false);
>  	if (ret)
> @@ -179,8 +184,10 @@ static int gpmi_init(struct gpmi_nand_data *this)
>  	 */
>  	writel(BM_GPMI_CTRL1_DECOUPLE_CS, r->gpmi_regs + HW_GPMI_CTRL1_SET);
>  
> -	return 0;

Please provide an explanation of the reasoning of this change is.

>  err_out:
> +	pm_runtime_mark_last_busy(this->dev);
> +	pm_runtime_put_autosuspend(this->dev);
> +
>  	return ret;
>  }
>  
> @@ -528,7 +535,7 @@ static int common_nfc_set_geometry(struct gpmi_nand_data *this)
>  static int bch_set_geometry(struct gpmi_nand_data *this)
>  {
>  	struct resources *r = &this->resources;
> -	int ret;
> +	int ret = 0;

I don't see any reason for this change.

>  	ret = common_nfc_set_geometry(this);
>  	if (ret)
> @@ -2676,7 +2682,7 @@ static int gpmi_nand_probe(struct platform_device *pdev)
>  	return 0;
>  
>  exit_nfc_init:
> -	pm_runtime_put(&pdev->dev);

I guess this is because of the change above that causes usage counter
not to be incremented in gpmi_init() when it is successful.

> +	pm_runtime_dont_use_autosuspend(&pdev->dev);

Is this required before pm_runtime_disable()?

>  	pm_runtime_disable(&pdev->dev);
>  	release_resources(this);
>  exit_acquire_resources:
> @@ -2688,7 +2694,6 @@ static int gpmi_nand_remove(struct platform_device *pdev)
>  {
>  	struct gpmi_nand_data *this = platform_get_drvdata(pdev);
>  
> -	pm_runtime_put_sync(&pdev->dev);

Should be covered by explanation of the change in gpmi_init().

>  	pm_runtime_disable(&pdev->dev);
>  
>  	nand_release(&this->nand);
> @@ -2700,10 +2705,12 @@ 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;
> +	pinctrl_pm_select_sleep_state(dev);
> +	ret = pm_runtime_force_suspend(dev);
> +
> +	return ret;
>  }
>  
>  static int gpmi_pm_resume(struct device *dev)
> @@ -2711,9 +2718,13 @@ 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;
> +	}
> +
> +	pinctrl_pm_select_default_state(dev);
>  
>  	/* re-init the GPMI registers */
>  	ret = gpmi_init(this);
> @@ -2729,22 +2740,40 @@ static int gpmi_pm_resume(struct device *dev)
>  		return ret;
>  	}
>  
> +	/* re-apply the timing setting */
> +	this->hw.must_apply_timings = true;
> +
>  	return 0;
>  }
>  #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)
> +
> +static int gpmi_runtime_suspend(struct device *dev)
>  {
>  	struct gpmi_nand_data *this = dev_get_drvdata(dev);
>  
> -	return __gpmi_enable_clk(this, false);
> +	gpmi_disable_clk(this);
> +	release_dma_channels(this);
> +
> +	return 0;
>  }
>  
> -static int __maybe_unused gpmi_runtime_resume(struct device *dev)
> +static int gpmi_runtime_resume(struct device *dev)
>  {
>  	struct gpmi_nand_data *this = dev_get_drvdata(dev);
> +	int ret;
>  
> -	return __gpmi_enable_clk(this, true);
> +	ret = gpmi_enable_clk(this);
> +	if (ret)
> +		return ret;
> +
> +	ret = acquire_dma_channels(this);
> +	if (ret < 0)
> +		return ret;
> +
> +	return 0;
>  }
>  
>  static const struct dev_pm_ops gpmi_pm_ops = {

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