Message ID | 20220216202655.194795-1-shreeya.patel@collabora.com |
---|---|
State | Accepted |
Commit | ae42f9288846353982e2eab181fb41e7fd8bf60f |
Headers | show |
Series | [v5] gpio: Return EPROBE_DEFER if gc->to_irq is NULL | expand |
On Wed, Feb 16, 2022 at 9:27 PM Shreeya Patel <shreeya.patel@collabora.com> wrote: > > We are racing the registering of .to_irq when probing the > i2c driver. This results in random failure of touchscreen > devices. > > Following explains the race condition better. > > [gpio driver] gpio driver registers gpio chip > [gpio consumer] gpio is acquired > [gpio consumer] gpiod_to_irq() fails with -ENXIO > [gpio driver] gpio driver registers irqchip > gpiod_to_irq works at this point, but -ENXIO is fatal > > We could see the following errors in dmesg logs when gc->to_irq is NULL > > [2.101857] i2c_hid i2c-FTS3528:00: HID over i2c has not been provided an Int IRQ > [2.101953] i2c_hid: probe of i2c-FTS3528:00 failed with error -22 > > To avoid this situation, defer probing until to_irq is registered. > Returning -EPROBE_DEFER would be the first step towards avoiding > the failure of devices due to the race in registration of .to_irq. > Final solution to this issue would be to avoid using gc irq members > until they are fully initialized. > > This issue has been reported many times in past and people have been > using workarounds like changing the pinctrl_amd to built-in instead > of loading it as a module or by adding a softdep for pinctrl_amd into > the config file. > > BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=209413 > Reviewed-by: Linus Walleij <linus.walleij@linaro.org> > Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com> > Reported-by: kernel test robot <lkp@intel.com> > Signed-off-by: Shreeya Patel <shreeya.patel@collabora.com> > > --- > Changes in v5 > - Improve explanation in commit message and sending it to the correct > email address. > > Changes in v4 > - Remove blank line and make the first letter of the sentence > capital. > > Changes in v3 > - Fix the error reported by kernel test robot. > > Changes in v2 > - Add a condition to check for irq chip to avoid bogus error. > --- > drivers/gpio/gpiolib.c | 10 ++++++++++ > 1 file changed, 10 insertions(+) > > diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c > index 3859911b61e9..a3d14277f17c 100644 > --- a/drivers/gpio/gpiolib.c > +++ b/drivers/gpio/gpiolib.c > @@ -3147,6 +3147,16 @@ int gpiod_to_irq(const struct gpio_desc *desc) > > return retirq; > } > +#ifdef CONFIG_GPIOLIB_IRQCHIP > + if (gc->irq.chip) { > + /* > + * Avoid race condition with other code, which tries to lookup > + * an IRQ before the irqchip has been properly registered, > + * i.e. while gpiochip is still being brought up. > + */ > + return -EPROBE_DEFER; > + } > +#endif > return -ENXIO; > } > EXPORT_SYMBOL_GPL(gpiod_to_irq); > -- > 2.30.2 > Queued for fixes, thanks! Bart
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index 3859911b61e9..a3d14277f17c 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -3147,6 +3147,16 @@ int gpiod_to_irq(const struct gpio_desc *desc) return retirq; } +#ifdef CONFIG_GPIOLIB_IRQCHIP + if (gc->irq.chip) { + /* + * Avoid race condition with other code, which tries to lookup + * an IRQ before the irqchip has been properly registered, + * i.e. while gpiochip is still being brought up. + */ + return -EPROBE_DEFER; + } +#endif return -ENXIO; } EXPORT_SYMBOL_GPL(gpiod_to_irq);