[PATCH 0/2] gpio: Allow userspace export from DT
Russell King - ARM Linux
linux at arm.linux.org.uk
Wed May 6 04:24:50 PDT 2015
On Mon, May 04, 2015 at 10:49:25AM +0200, Johan Hovold wrote:
> Firmware should describe pin directionality and function, and undefined
> pins should never be allowed to be accessed from userspace.
No, that's totally wrong if you consider one of the most common use
cases out there...
Think about something like a Raspberry Pi, where you have a header with
GPIOs on it, which can be used for multiple different purposes (and are
even multiplexed with some on-SoC functions.)
"Firmware" can't know about all possible configurations of those IO pins.
That's why Raspberry Pi uses a userspace helper and programs stuff up
appropriately for the users application.
FTTC broadband for 0.8mile line: currently at 10.5Mbps down 400kbps up
according to speedtest.net.
More information about the linux-arm-kernel