On Fri, Sep 5, 2014 at 6:38 PM, Johan Hovold <johan@xxxxxxxxxx> wrote:
> On Fri, Sep 05, 2014 at 06:17:59PM +0300, Octavian Purdila wrote:
>
>> +static int dln2_do_remove(struct dln2_gpio *dln2)
>> +{
>> + /* When removing the DLN2 USB device, gpiochip_remove may fail
>> + * due to i2c drivers holding a GPIO pin. However, the i2c bus
>> + * will eventually be removed triggering an i2c driver remove
>> + * which will release the GPIO pin. So retrying the operation
>> + * later should succeed. */
>> + int ret = gpiochip_remove(&dln2->gpio);
>> + struct device *dev = dln2->gpio.dev;
>> +
>> + if (ret < 0) {
>> + if (ret == -EBUSY)
>> + schedule_delayed_work(&dln2->remove_work.work, HZ/10);
>> + else
>> + dev_warn(dev, "error removing gpio chip: %d\n", ret);
>> + } else {
>> + kfree(dln2);
>> + }
>> +
>> + return ret;
>> +}
>
> Apparently, the return value from gpiochip_remove is going away:
>
> "Start to kill off the return value from gpiochip_remove() by
> removing the __must_check attribute and removing all checks
> inside the drivers/gpio directory. The rationale is: well what
> were we supposed to do if there is an error code? Not much:
> print an error message. And gpiolib already does that. So make
> this function return void eventually."
>
> https://www.mail-archive.com/linux-gpio@xxxxxxxxxxxxxxx/msg03468.html
>
Oh, I missed this, thanks for pointing it out.
> Also, have you considered what happens if there are gpios exported
> through sysfs? These may never be released.
>
> In general, how well have these patches been tested with disconnect
> events? At least gpiolib is known to blow up (sooner or later) when a
> gpiochip is removed when having requested gpios.
>
I do disconnect tests regularly. Since switching to the new irq
interface the following patch is needed:
https://lkml.org/lkml/2014/9/5/408
With it and the current patch sets things seems to work well.
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