lkml.org 
[lkml]   [2023]   [Nov]   [5]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    From
    Date
    SubjectRe: [RFC v5 0/4] firmware: arm_scmi: Add SCMI v3.2 pincontrol protocol basic support
    Hi Oleksii,

    thanks for this patch, which still looks very good to me.

    A question that was raised in discussion with Takahiro Akashi was how we
    identify pins that can be used for GPIO and if the spec or implementation
    has given any thought to that.

    I can think of a few, such that:

    1. Pins that can be used for GPIO all belong to some group - possibly even
    one group per pin such as "gpioA1", "gpioA2", "gpioA3" etc - that can be
    assigned a function named "gpio" or similar.

    2. GPIO is seen as something external or "third usecase" that is handled
    by pin config, not by pin mux.

    If it is 1 - which I find likely - it would be good to standardize the name of
    the function to be "gpio" and somehow make it clear that all pins that are
    desired to be used for GPIO need to have a (group, function) tuple pair
    such as ("gpio001", "gpio") that will put the pin into GPIO mode.

    If the assumption is anything goes, i.e. a vendor could say something
    like ("io-group-99", "generic-io") to put a certain pin into GPIO mode,
    that is maybe not so optimal, because it's nice for the GPIO driver
    (which will come up) to be able to figure out by e.g. string name
    conventions that a pin is in GPIO mode, and which group and function
    that will put it into GPIO mode.

    If this generality is not desired, having standard names for GPIO
    functions and groups is still going to be an upside, if it can be achieved.
    But maybe this isn't attainable at this point?

    Yours,
    Linus Walleij

    \
     
     \ /
      Last update: 2023-11-20 13:48    [W:2.097 / U:0.208 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site