[OpenWrt-Devel] [PATCH 4/6] gpio: gemini: rename to match Faraday IP
linus.walleij at linaro.org
Thu Mar 23 08:47:20 EDT 2017
On Wed, Mar 22, 2017 at 11:21 AM, Jonas Jensen <jonas.jensen at gmail.com> wrote:
> On 22 March 2017 at 09:42, Linus Walleij <linus.walleij at linaro.org> wrote:
>> Nice! Have you tested my new GPIO character device tools from
>> tools/gpio/* in the kernel tree?
> I had not and thanks for pointing that out, lsgpio lists all available
> gpios (though most of them are unnamed), and gpio-hammer successfully
> toggled buzzer on/off.
> GPIO chip: gpiochip0, "FTGPIO010", 32 GPIO lines
> line 0: unnamed unused [output]
> line 1: unnamed unused [output]
> line 2: unnamed unused [output]
> line 3: unnamed unused [output]
BTW you can name all the "unnamed" lines by using
gpio-line-names in the gpio node of the device tree, c.f.
> line 24: unnamed unused [output]
> line 25: unnamed unused
> line 26: unnamed unused
> line 27: unnamed "ready-led" [kernel output active-low]
> ./gpio-hammer -n gpiochip0 -o 24
> Hammer lines  on gpiochip0, initial states: 
> [|] [24: 1]
> ./gpio-hammer -n gpiochip0 -o 27
> Failed to issue GET LINEHANDLE IOCTL (-16)
So finally when the kernel is using a GPIO line you can't use it
from userspace at the same time. -16 is -EBUSY.
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