lkml.org 
[lkml]   [2022]   [Mar]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 5.16 076/121] gpio: Return EPROBE_DEFER if gc->to_irq is NULL
    Date
    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 a1dca6dc03b4..dcb0dca651ac 100644
    --- a/drivers/gpio/gpiolib.c
    +++ b/drivers/gpio/gpiolib.c
    @@ -3121,6 +3121,16 @@ 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);
    --
    2.34.1


    \
     
     \ /
      Last update: 2022-03-14 13:37    [W:2.229 / U:0.168 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site