On Thursday, July 5, 2018 7:50:37 AM CEST Lee Jones wrote: > On Wed, 04 Jul 2018, Janusz Krzysztofik wrote: > > On Tuesday, July 3, 2018 7:31:41 PM CEST Boris Brezillon wrote: > > > Hi Janusz, > > > > > > On Tue, 3 Jul 2018 19:26:35 +0200 > > > > > > Janusz Krzysztofik <jmkrzyszt@xxxxxxxxx> wrote: > > > > Avoid replication of error code conversion in non-DT GPIO consumers' > > > > code by returning -EPROBE_DEFER from gpiod_find() in case a chip > > > > identified by its label in a registered lookup table is not ready. > > > > > > > > See https://lkml.org/lkml/2018/5/30/176 for example case. > > > > > > > > Signed-off-by: Janusz Krzysztofik <jmkrzyszt@xxxxxxxxx> > > > > --- > > > > If accepted, please add > > > > > > > > Suggested-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxx> > > > > > > > > if Boris doesn't mind. > > > > > > > > Thanks, > > > > Janusz > > > > > > > > drivers/gpio/gpiolib.c | 13 ++++++++++--- > > > > 1 file changed, 10 insertions(+), 3 deletions(-) > > > > > > > > diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c > > > > index e11a3bb03820..15dc77c80328 100644 > > > > --- a/drivers/gpio/gpiolib.c > > > > +++ b/drivers/gpio/gpiolib.c > > > > @@ -3639,9 +3639,16 @@ static struct gpio_desc *gpiod_find(struct > > > > device > > > > *dev, const char *con_id,> > > > > > > > > chip = find_chip_by_name(p->chip_label); > > > > > > > > if (!chip) { > > > > > > > > - dev_err(dev, "cannot find GPIO chip %s\n", > > > > - p->chip_label); > > > > - return ERR_PTR(-ENODEV); > > > > + /* > > > > + * As the lookup table indicates a chip with > > > > + * p->chip_label should exist, assume it may > > > > + * still appear latar and let the interested > > > > > > > ^ later > > > > > > > > + * consumer be probed again or let the Deferred > > > > + * Probe infrastructure handle the error. > > > > + */ > > > > + dev_warn(dev, "cannot find GPIO chip %s, deferring\n", > > > > + p->chip_label); > > > > + return ERR_PTR(-EPROBE_DEFER); > > > > > > > > } > > > > > > > > if (chip->ngpio <= p->chip_hwnum) { > > > > > > Looks good otherwise. Let's hope we're not breaking implementations > > > testing for -ENODEV... > > > > I've reviewed them all and found two which I think may be affected: > > - drivers/mfd/arizona-core.c, > > - drivers/i2c/busses/i2c-imx.c. > > As far as I can understand the code, both depend on error != -EPROBE_DEFER > > in order to continue in degraded mode. I'm adding their maintainers to > > the loop. > From a quick glance, the -EPROBE_DEFER handing in Arizona Core appears > to be correct. Would you mind explaining what your concerns are in > more detail please? Hi That's more about handling -ENODEV rather than -EPROBE_DEFER. Before the change, if GPIO chip supposed to provide "reset" pin was not ready during arizona_dev_init(), devm_gpiod_get() returned -ENODEV and device was initialized in degraded mode, i.e., with no control over the "reset" pin. After the change, gpiod_get() will return -EPROBE_DEFER in such case and arizona_dev_init() won't succeed in case the GPIO chip doesn't appear later for some reason. Thanks, Januszz
