On Thu, Sep 25, 2014 at 9:17 PM, Michael Welling <mwell...@emacinc.com> wrote:
> How do I register a GPIO for use in the PHY suspend and resume code? > Can it be handled outside of the PHY driver? Nominally these days you should get a named GPIO using the GPIO descriptor abstraction, putting a named GPIO reference in the device tree node for the PHY, which should work fine if you're using device tree for this system. Documentation/gpio/consumer.txt > If so how do ensure the appropriate suspend and resume sequencing? AFAICT there is no good answer to this kind of questions. I guess my best answer would be something like what has been said for DRM drivers: handle all the sequence-sensitive hardware in one big composite driver and handle sequencing in the driver. > For reference, we are using a Micrel KSZ8081 PHY connected to a > AT91SAMA5D35 processor. I don't know how AT91 is progressing on the device tree side or if it's strictly required to boot these days. If it is, you should be able to proceed as indicated. > Addendum: > I ran into another situation where a GPIO enabled oscillator was used. > The oscillator in this case drives the master clock for a audio codec. > In the old days (before device tree), I could initialize the GPIO in the > platform board file. Now with device tree I can setup the pin multipler > but the initial state of the GPIO I am not sure how to set. A driver needs to do this. Like a drivers/clk driver in this case I guess? > Is there a way to directly change the state of a GPIO pin from a > devicetree entry? I have suggested mechanisms like GPIO hogs to replace the need for very basic drivers that would just take a GPIO during init, set it and never do anything with it. Like the gpiochip node should have some hog entries: gpio-hog-high = <0>, <1>, <2>...; gpio-hog-low = <...>; Then they would be taken away from other consumers and not possible to use for anything. This has so far not been implemented though. Yours, Linus Walleij -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
