Hi Linus, > -----Original Message----- > From: Linus Walleij <[email protected]> > Sent: Thursday, January 7, 2021 3:17 PM > To: Srinivas Neeli <[email protected]> > Cc: Bartosz Golaszewski <[email protected]>; Michal Simek > <[email protected]>; Shubhrajyoti Datta <[email protected]>; Srinivas > Goud <[email protected]>; Robert Hancock <[email protected]>; > William Breathitt Gray <[email protected]>; Syed Nayyar Waris > <[email protected]>; open list:GPIO SUBSYSTEM <linux- > [email protected]>; Linux ARM <[email protected]>; > [email protected]; git <[email protected]> > Subject: Re: [PATCH V4 4/5] gpio: gpio-xilinx: Add support for suspend and > resume > > On Wed, Jan 6, 2021 at 1:27 PM Srinivas Neeli <[email protected]> > wrote: > > > Add support for suspend and resume, pm runtime suspend and resume. > > Added free and request calls. > > > > Signed-off-by: Srinivas Neeli <[email protected]> > (...) > > > +static int xgpio_request(struct gpio_chip *chip, unsigned int offset) > > +{ > > + int ret; > > + > > + ret = pm_runtime_get_sync(chip->parent); > > + /* > > + * If the device is already active pm_runtime_get() will return 1 on > > + * success, but gpio_request still needs to return 0. > > + */ > > + return ret < 0 ? ret : 0; > > +} > > That's clever. I think more GPIO drivers should be doing it like this, today I > think most just ignore the return code. > > > +static int __maybe_unused xgpio_suspend(struct device *dev) static > > +int __maybe_unused xgpio_resume(struct device *dev) > > Those look good. > > > > /** > > * xgpio_remove - Remove method for the GPIO device. > > * @pdev: pointer to the platform device @@ -289,7 +323,10 @@ static > > int xgpio_remove(struct platform_device *pdev) { > > struct xgpio_instance *gpio = platform_get_drvdata(pdev); > > > > - clk_disable_unprepare(gpio->clk); > > + if (!pm_runtime_suspended(&pdev->dev)) > > + clk_disable_unprepare(gpio->clk); > > + > > + pm_runtime_disable(&pdev->dev); > > This looks complex and racy. What if the device is resumed after you > executed the first part of the statement.
Could you please explain more on this. What is the need to call pm_runtime_get_sync(); in remove API ? > > The normal sequence is: > > pm_runtime_get_sync(dev); > pm_runtime_put_noidle(dev); > pm_runtime_disable(dev); > > This will make sure the clock is enabled and pm runtime is disabled. > After this you can unconditionally call clk_disable_unprepare(gpio->clk); > > It is what you are doing on the errorpath of probe(). > > Yours, > Linus Walleij
