Re: [PATCH] gpio: keep the GPIO line names internal

[Markus Pargmann <mpa@pengutronix.de>]

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On Sun, Oct 04, 2015 at 03:37:42PM +0200, Johan Hovold wrote:
> On Wed, Sep 23, 2015 at 04:27:33PM -0700, Linus Walleij wrote:
> > This refactors the changes to the GPIO line naming mechanism to
> > not have so widespread effects, instead we conclude the patch series
> > by having created a name attribute in the GPIO descriptor, that need
> > not be globally unique, and it will be initialized from the old
> > .names array in struct gpio_chip if it exists, then used in the legacy
> > sysfs code like the array was used previously.
> > 
> > The associated changes to name lines from the device tree are
> > controversial and need to stand alone from this. Resulting changes:
> > 
> > 1. Remove the export and the header for the gpio_name_to_desc() as so
> > far the only use is inside gpiolib.c. Staticize gpio_name_to_desc()
> > and move it above the only function using it.
> > 
> > 2. Only print a warning if there are two GPIO lines with the same name.
> > The reason is to preserve current behaviour: before the previous
> > changes to the naming mechanism this would not reject probing the
> > driver, instead the error would occur when trying to export the line
> > in sysfs, so restore this behaviour, but print a friendly warning
> > if names collide.
> 
> This looks good (apart from the checkpatch warning for the warning
> message string).
> 
> You also need to revert ddd5404007b8 ("gpio-sysfs: Use gpio descriptor
> name instead of gpiochip names array") however as this is an ABI change.  
> Otherwise pins with a name in DT will now be exported using the gpio name
> rather than number as they used to be. [ The current behaviour is
> maintained by exporting names from chip->names for hard coded names
> only. ]

Even for GPIOs from DT it is not a ABI change. The only GPIOs that have
a GPIO name at the moment are using the GPIO hogging mechanism. But
hogged GPIOs can't be exported to userspace so there is no difference
for these.

Best Regards,

Markus

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