On Wed, May 06, 2015 at 03:25:20PM +0200, Johan Hovold wrote: > On Wed, May 06, 2015 at 01:57:08PM +0100, Russell King - ARM Linux wrote: > > There is *no* "firmware" on these devices. The only thing you have is a > > boot loader and a DT blob, and people will hate you if you tell them that > > they have to change the DT blob and then reboot their systems to change > > the functionality of a GPIO pin. > > > > It's also entirely reasonable to assume that people are going to want to > > change the configuration at runtime, given their diverse range of > > applications. > > DT can be changed at run-time using overlays. Yes, I'm aware of that, but that code is really not nice. There is no notification system to drivers that something has changed, and with a GPIO driver, you really don't want the driver to be unbound and re-bound just because something changed. That has the very real possibility to disrupt users of other GPIOs. I'm not sure what kind of driver you'd attach userspace GPIO pinctrl settings to other than the GPIO driver. Sure, if you're wanting to configure a couple of GPIOs as I2C, then yes, you certainly should put the binding in the I2C device block in DT, but you don't always have a device to do that with. > You also cut out the part in my reply about continuing to allow > unrestricted access for such cases. That could still continue to be the > default (e.g. when there are no pin function names defined in DT). Yes, that's standard Internet email etiquette - cut everything from the message you're replying to which is not part of the context of the immediate reply. I'd include a URL to that, but unfortunately google seems broken (it's inserting a refresh into the results page which causes elinks to continually refetch the same page, eventually triggering a violation of googles terms of use... yea, quite funny that google is instructing browsers to violate their own terms of use.) -- FTTC broadband for 0.8mile line: currently at 10.5Mbps down 400kbps up according to speedtest.net. -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
