Re: [PATCH] gpio sysfs: add a "toggle" value

[Mike Frysinger <vapier.adi@gmail.com>]

On Thu, Jun 4, 2009 at 04:27, David Brownell wrote:
> On Thursday 04 June 2009, Mike Frysinger wrote:
>> > A suitable place to document this is Documentation/gpio.txt.
>>
>> yes, but i wanted to make sure David didnt reject the idea before i
>> spend time writing documentation.
>
> My initial reaction was that the function is somewhat superfluous,
> so having a use case in the patch comment would be good:  why
> can't userspace do the toggle itself?

when people were using the simple-gpio driver i wrote (which had
pretty much function parity with the sysfs implementation), i had a
customer or two ask for toggle for their systems.  i didnt get details
for why they wanted a toggle however ... they wanted it in their app
and adding it was trivial.

> On the other hand, I find it hard to object to such a small feature.
> If that's the worst feature bloat in Linux this year, we're overdue
> for a big party.  ;)

my next request was for a 1 letter command set and chaining
operations.  say you want to toggle a gpio line 4 times, having to go
between kernel and userspace for that seems kind of heavy.
echo TTTT > value
-mike