From: Shreeya Patel shreeya.patel@collabora.com
[ Upstream commit ae42f9288846353982e2eab181fb41e7fd8bf60f ]
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 Signed-off-by: Bartosz Golaszewski brgl@bgdev.pl Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/gpio/gpiolib.c | 10 ++++++++++ 1 file changed, 10 insertions(+)
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index 12472b84a71ca..b66e3f2ca1b1e 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -3327,6 +3327,16 @@ 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);