Re: [PATCH 2/2] tools/gpio: add the gpio-hammer tool

[Michael Welling <mwelling@ieee.org>]

On Tue, May 31, 2016 at 01:59:42PM +0200, Linus Walleij wrote:
> On Wed, Apr 27, 2016 at 6:00 PM, Michael Welling <mwelling@ieee.org> wrote:
> > On Tue, Apr 26, 2016 at 10:54:26AM +0200, Linus Walleij wrote:
> >> The gpio-hammer is used from userspace as an example of how
> >> to retrieve a GPIO handle for one or several GPIO lines and
> >> hammer the outputs from low to high and back again. It will
> >> pulse the selected lines once per second for a specified
> >> number of times or indefinitely if no loop count is
> >> supplied.
> >>
> >> Example output:
> >> $ gpio-hammer -n gpiochip0 -o5 -o6 -o7
> >> Hammer lines [5, 6, 7] on gpiochip0, initial states: [1, 1, 1]
> >> [-] [5: 0, 6: 0, 7: 0]
> >>
> >> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
> >
> > Tested-by: Michael Welling <mwelling@ieee.org>
> 
> Thanks! :)

No problem. I wish I could help more.
I like how the support has progressed.

Did you ever find a solution for the exhausted char dev problem?

> 
> > Below is the output from my target.
> 
> You can now get rid of all the "unnamed" in the first column
> by supplying the line/rail names in gpio-line-names = "A", "B" ...;
> in the GPIO controller node in the device tree for the platform,
> if it uses device tree too boot.

Yeah I saw that.. not bored enough to name all of the GPIOs.

> 
> > You will notice that a kernel warning is
> > spewed out if I use the mcp23s08.
> > The processor GPIOs work fine as verified by blinking LEDs.
> >
> > root@som3517-som200:~# ./lsgpio
> > GPIO chip: gpiochip4, "mcp23s08", 8 GPIO lines
> >         line  0: unnamed unused
> >         line  1: unnamed unused
> >         line  2: unnamed unused
> >         line  3: unnamed unused
> >         line  4: unnamed unused
> >         line  5: unnamed unused
> >         line  6: unnamed unused
> >         line  7: unnamed unused
> 
> > root@som3517-som200:~# ./gpio-hammer -n gpiochip4 -o0
> > [  187.511606] ------------[ cut here ]------------
> > [  187.516949] WARNING: CPU: 0 PID: 830 at /home/michael/projects/linux/linux-git/drivers/gpio/gpiolib.c:1907 gpiod_get_value+0x60/0xa4
> 
> Ah that's right, I have to use gpiod_get_value_cansleep(). Will
> fix that.
> 
> Yours,
> Linus Walleij