Hi all,
Dne 28.10.2014 v 18:28 Pantelis Antoniou napsal(a):
Hi Linus,
On Oct 28, 2014, at 19:09 , Linus Walleij <linus.walleij@xxxxxxxxxx> wrote:
On Wed, Oct 22, 2014 at 11:58 AM, Pantelis Antoniou
<panto@xxxxxxxxxxxxxxxxxxxxxxx> wrote:
On Oct 22, 2014, at 12:41 PM, Alexandre Courbot <gnurou@xxxxxxxxx> 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.
Yes.
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.
That would be nice for me too, I'll try it later, now I have more urgent work.
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
Yours
Jiri
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