* Linus Walleij <linus.walleij@xxxxxxxxxx> [140523 04:36]: > On Fri, May 16, 2014 at 12:15 PM, Peter TB Brett <peter@xxxxxxxxxxxxx> wrote: > > The current call chain seems to be: gpiod_export() --> gpiod_request() --> > > omap_gpio_request(). Looking at other GPIO drivers, it seems like > > omap_gpio_request() should eventually call pinctrl_request_gpio(). Would be > > useful if someone who knows about OMAP4/gpio/pinctrl could take a look at > > this. If we do this, we also need a solution to prevent automatic remuxing of GPIO pins from happending. For wake-up events, some drivers need to remux a rx pin to GPIO input for the duration of idle, and then back to device rx pin. This is needed on some other platforms too AFAIK. For the drivers needing GPIO wake-up events, request_gpio is done in the driver after drivers/base/pinctrl.c has already muxed the device pin to rx. At minimum we would get warnings about reserved pins if we tried to automatically mux them to GPIO. We may be able to use some GPIO specific property to prevent automatic remuxing as we discussed in the #armlinux few days ago. Related to automatic remuxing of GPIO pins, there are also other needs for pinctrl and GPIO interaction. We need to remux GPIO output pins to input + pull + safe_mode to prevent the GPIO pins losing value briefly during off-idle. That's the gpio errata 1.158 at as shown at least at [1]. Because the GPIO to pinctrl mapping is sparse and SoC specific, there's currently now obvious way to do that. And we would need few new GPIO functions to tell pinctrl subsystem about the change. Regards, Tony [1] https://www.gitorious.org/rowboat/kernel/commit/86b15f21298b749a9d8216ff1839d33ad542464e?format=patch -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
