Hi Linus, > On Oct 28, 2014, at 19:09 , Linus Walleij <[email protected]> wrote: > > On Wed, Oct 22, 2014 at 11:58 AM, Pantelis Antoniou > <[email protected]> wrote: >>> On Oct 22, 2014, at 12:41 PM, Alexandre Courbot <[email protected]> wrote: > >>> Pinmux configuration sounds like a job for pinmux more than GPIO, and >>> exporting potentially many GPIOs to user-space sounds like a work for >>> a proper driver. >> >> I’m afraid that’s not the case. A great many users (...) > > How many are many? How long is a piece of string? "Many" may > refer to every system on the market or me and my friends. > That claim has to be more specific. >
On every embedded product board that I have worked on for a customer, invariably user-space GPIO was required for some odd pieces of hardware. I guess that’s in the dozen range for me, and Jiri that originally posted seems to be doing something similar too. >> do not require anything >> more than setting a pinmux > > Which can be done (from device tree if need be) using pin control > hogs. > >> and the GPIO configuration (input/output). > > And we have GPIO hogs for that in the pipe. > The original proposal was on January, and there’s a RFC posted just a few days back. I will take a look. >> They can then do low speed I/O using the sysfs interface, without having to >> use any complex APIs (shell works just fine). > > So what is added is export capability, which could be done by supplanting > the GPIO hogging mechanism with some linux,export thing. > Yes, that would be nice. >> Think of stuff like controlling a sprinkler valve, or something like a >> mechanical >> door detection open state. > > OK it's in the department of automatic control, which is arguably the > only technical area where userspace GPIO handling actually makes > sense. > Err, let’s just say that I completely disagree, but whatever. If the new GPIO hogging methods make it in mainline along with the export mechanism it’d be fine by me. > Yours, > Linus Walleij Regards — Pantelis -- To unsubscribe from this list: send the line "unsubscribe linux-gpio" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
