Re: [PATCH 4/5] gpiolib: handle deferral probe error

G, Manjunath Kondaiah
2011-10-12T06:14:32Z

On Fri, Oct 07, 2011 at 04:09:38PM -0600, Grant Likely wrote:
> On Fri, Oct 7, 2011 at 4:06 AM, Alan Cox <alan@lxorguk.ukuu.org.uk> wrote:
> > On Fri, 07 Oct 2011 10:33:09 +0500
> > "G, Manjunath Kondaiah" <manjugk@ti.com> wrote:
> >
> >>
> >> The gpio library should return -EPROBE_DEFER in gpio_request
> >> if gpio driver is not ready.
> >
> > Why not use the perfectly good existing error codes we have for this ?
> >
> > We have EAGAIN and EUNATCH both of which look sensible.
>
> I want a distinct error code for probe deferral so that a) it doesn't
> overlap with something a driver is already doing, and b) so that all
> the users can be found again at a later date.
>
> That said, I'm not in agreement with this patch. It is fine for gpio
> lib to have a code that means the pin doesn't exist (yet), but the
> device driver needs to be the one to decide whether or not it is
> appropriate to use probe deferral.

During gpio_request, driver gpio_request is not available. How can we expect
driver to request deferred probe in this case?

-M