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

[Han Xu <xhnjupt@xxxxxxxxx>]

On Thu, Jan 9, 2020 at 2:46 PM Esben Haabendal <esben@xxxxxxxxxx> wrote:
>
> 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.

removed.

>
> > +
> > +     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.

I prefer to pair all runtime ops in same function, get_sync before
register access and put after that, in all cases.

>
> >  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.

removed

>
> >       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()?

If probe function failed before runtime timeout, for instance, the
NAND chip not mounted, the runtime suspend won't be called without
this change.

>
> >       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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-- 
Sincerely,

Han XU

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