Messages in this thread | | | Date | Fri, 5 Sep 2014 19:04:51 +0300 | Subject | Re: [PATCH v3 3/3] gpio: add support for the Diolan DLN-2 USB GPIO driver | From | Octavian Purdila <> |
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On Fri, Sep 5, 2014 at 6:38 PM, Johan Hovold <johan@kernel.org> 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@vger.kernel.org/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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