Hello Geert, On Fri, Mar 03, 2017 at 08:21:05PM +0100, Geert Uytterhoeven wrote: > > diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c > > index 91e7dddbf72c..2f4cdd4e7b4f 100644 > > --- a/drivers/tty/serial/sh-sci.c > > +++ b/drivers/tty/serial/sh-sci.c > > @@ -3022,7 +3022,7 @@ static int sci_probe_single(struct platform_device *dev, > > return ret; > > > > sciport->gpios = mctrl_gpio_init(&sciport->port, 0); > > - if (IS_ERR(sciport->gpios) && PTR_ERR(sciport->gpios) != -ENOSYS) > > + if (IS_ERR(sciport->gpios)) > > return PTR_ERR(sciport->gpios); > > Now the sh-sci driver fails to probe on legacy platforms where GPIOLIB=n. > The check for -ENOSYS made it succeed before. That's right, intended and the only option that's save (for some definition of save; the obvious downside is that there is no /dev/tty$whatever for you). Ignoring -ENOSYS is only ok if your device doesn't have a cts-gpio. If it has, ignoring -ENOSYS hides bugs because the driver sends data while it shouldn't or cannot signal the other side that it should stop (or start) a transmission. So the options are: - enable GPIOLIB (maybe enforce that by letting the driver select it) - introduce a CONFIG_HALFGPIOLIB that makes gpiod_get_optional and mctrl_gpio_init return only then -ENOSYS if there is a gpio specified and NULL otherwise. > > Then mctrl_gpio_to_gpiod isn't called. I don't have a machine to test > > this, but I think currently this makes the machine barf to continue > > here because with sciport->gpios = ERR_PTR(-ENOSYS) calling > > > > mctrl_gpio_to_gpiod(sciport->gpios, ...) > > > > is a bad idea. > > If sciport->gpios == ERR_PTR(-ENOSYS), CONFIG_GPIOLIB is not enabled, the > feature is not available, and mctrl_gpio_to_gpiod() will not > dereference the error > pointer. Ah, makes sense. > >> Perhaps mctrl_gpio_to_gpiod() should always return NULL if !CONFIG_GPIOLIB? > > > > No, mctrl_gpio_to_gpiod is right. You are only supposed to call it if > > mctrl_gpio_init succeeded. > > Then I have to add checks for sciport->gpios == ERR_PTR(-ENOSYS)... No, ignoring -ENOSYS is wrong. Best regards Uwe -- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | http://www.pengutronix.de/ | -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
