Hi Linus, On Mon, May 2, 2016 at 10:30 AM, Linus Walleij <linus.walleij@xxxxxxxxxx> wrote: > On Mon, May 2, 2016 at 10:03 AM, Geert Uytterhoeven > <geert@xxxxxxxxxxxxxx> wrote: >> On Sun, May 1, 2016 at 10:48 AM, Linus Walleij <linus.walleij@xxxxxxxxxx> wrote: >>>> - Drivers that call irq_find_mapping(), irq_create_mapping(), or >>>> irq_create_fwspec_mapping() return zero! This also applies to the >>>> core helper gpiochip_to_irq(). >>> >>> Zero means NO_IRQ. >>> >>> Reminder: >>> http://lwn.net/Articles/470820/ >>> >>> What we should do is patch all drivers to return 0 on failure, and >>> patch any consumers like mctrl_gpio_init() to handle that correctly. >> >> That's the Long Term Plan. There are still too many non-zero NO_IRQ >> definitions in use... >> >> Is -ENXIO acceptable for the short term? > > I don't understand. You say you have a problem with > mctrl_gpio_init() which looks like this: > > ret = gpiod_to_irq(gpios->gpio[i]); > if (ret <= 0) { > dev_err(port->dev, (...) > > This function is already *correctly* handling zero as NO_IRQ > i.e. an error. > > Just make your driver return 0/NO_IRQ and it is fixed. > > Or are there other problems that you're not telling about? "mctrl_gpio_init() returns -ENOSYS if GPIOLIB is not enabled, which is intended to be ignored by its callers. However, ignoring -ENOSYS when it was caused by a gpiod_to_irq() failure will lead to a crash later:" Please see the !CONFIG_GPIOLIB stubs in drivers/tty/serial/serial_mctrl_gpio.h. Hence -ENOSYS is to be ignored by the driver, and it's safe to call any of the mctrl_gpio_*() helpers if !CONFIG_GPIOLIB. That was done so drivers don't have to check for !CONFIG_GPIOLIB theirselves. However, if CONFIG_GPIOLIB=y, and -ENOSYS was a real error, calling any of the mctrl_gpio_*() helpers will cause a crash. Without testing for CONFIG_GPIOLIB, there's no way the driver can know -ENOSYS was a real error. Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
