On Fri, 2016-04-22 at 16:59 +0300, Jarkko Nikula wrote:
> Hi
>
> On 04/22/2016 11:49 AM, Jisheng Zhang wrote:
> >
> > If i2c_dw_probe() fails, we should disable and unprepare the clock,
> > otherwise the clock enable and prepare is left unbalanced.
> >
> > In dw_i2c_plat_remove(), we'd better to not rely on runtime PM to
> > disable and unprepare the clock since CONFIG_PM may be disabled when
> > configuring the kernel. So we explicitly disable and unprepare the
> > clock in dw_i2c_plat_remove() rather than implicitly rely on
> > pm_runtime_put_sync(). To keep the device usage count balanced, we
> > call pm_runtime_put_noidle() to decrease the usage count.
> >
> > Signed-off-by: Jisheng Zhang <jszhang@xxxxxxxxxxx>
> > ---
> > Since v3:
> > - use runtime PM rather than rpm in commit msg
> > - remove duplicated "(" in commit msg
> >
> > Since v2:
> > - s/clk/clock
> > - describe why use pm_runtime_put_noidle()
> >
> > Since v1:
> > - fix commit msg: "not rely on rpm" rather than "rely on rpm"
> > - call i2c_dw_plat_prepare_clk after pm_rumtime_disable()
> > drivers/i2c/busses/i2c-designware-platdrv.c | 16 ++++++++++------
> > 1 file changed, 10 insertions(+), 6 deletions(-)
> >
> > diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c
> > b/drivers/i2c/busses/i2c-designware-platdrv.c
> > index d656657..a771781 100644
> > --- a/drivers/i2c/busses/i2c-designware-platdrv.c
> > +++ b/drivers/i2c/busses/i2c-designware-platdrv.c
> > @@ -253,8 +253,11 @@ static int dw_i2c_plat_probe(struct
> > platform_device *pdev)
> > }
> >
> > r = i2c_dw_probe(dev);
> > - if (r && !dev->pm_runtime_disabled)
> > - pm_runtime_disable(&pdev->dev);
> > + if (r) {
> > + if (!dev->pm_runtime_disabled)
> > + pm_runtime_disable(&pdev->dev);
> > + i2c_dw_plat_prepare_clk(dev, false);
> > + }
> >
> > return r;
> > }
> > @@ -264,15 +267,16 @@ static int dw_i2c_plat_remove(struct
> > platform_device *pdev)
> > struct dw_i2c_dev *dev = platform_get_drvdata(pdev);
> >
> > pm_runtime_get_sync(&pdev->dev);
> > + pm_runtime_dont_use_autosuspend(&pdev->dev);
> > + if (!dev->pm_runtime_disabled)
> > + pm_runtime_disable(&pdev->dev);
> > + pm_runtime_put_noidle(&pdev->dev);
> >
> > i2c_del_adapter(&dev->adapter);
> >
> > i2c_dw_disable(dev);
> >
> > - pm_runtime_dont_use_autosuspend(&pdev->dev);
> > - pm_runtime_put_sync(&pdev->dev);
> > - if (!dev->pm_runtime_disabled)
> > - pm_runtime_disable(&pdev->dev);
> > + i2c_dw_plat_prepare_clk(dev, false);
> >
> This feels a bit an invasive change to me for unbalanced clock
> enable/disable and I noticed this changes semantics how
> drivers/acpi/acpi_lpss.c devices are shutdown when removing the
> driver.
> Although I didn't notice does it cause any regression.
>
> Before patch:
> 1. drivers/base/dd.c: __device_release_driver()
> - pm_runtime_get_sync()
> -> acpi_device_set_power(D0)
> acpi_lpss_restore_ctx()
> dw_i2c_plat_resume()
> 2. dw_i2c_plat_remove()
> - pm_runtime_dont_use_autosuspend()
> pm_runtime_put_sync()
> -> dw_i2c_plat_suspend()
> acpi_lpss_save_ctx()
> acpi_device_set_power(D3)
> 3. __device_release_driver() continue
> - dev->pm_domain->dismiss(dev)
> -> acpi_lpss_dismiss() ... -> acpi_device_set_power(D3)
>
> After patch:
> 1. drivers/base/dd.c: __device_release_driver()
> - pm_runtime_get_sync()
> -> acpi_device_set_power(D0)
> acpi_lpss_restore_ctx()
> dw_i2c_plat_resume()
> 2. dw_i2c_plat_remove()
> - pm_runtime_dont_use_autosuspend()
> pm_runtime_put_noidle()
> * no device suspending and acpi_lpss_save_ctx()
> 3. __device_release_driver() continue
> - dev->pm_domain->dismiss(dev)
> -> acpi_lpss_dismiss() ... -> acpi_device_set_power(D3)
> * powers down here
>
> So after patch there is no acpi_lpss_save_ctx() call but I don't see
> does it cause any issue here. Maybe it's better to track clock only.
> What you think Andy?
Now it looks like two fixes in one patch. From the commit message I
didn't get the relation between change runtime PM call (one to the
other) and clock (un)preparation.
--
Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Intel Finland Oy
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