[PATCH 3.9] Driver for 7-segment displays connected over GPIOs
Thomas Petazzoni
thomas.petazzoni at free-electrons.com
Mon Jan 7 12:07:08 EST 2013
Dear Greg Kroah-Hartman,
On Mon, 7 Jan 2013 08:48:45 -0800, Greg Kroah-Hartman wrote:
> If you ever add/remove/modify sysfs files, you have to also do the same
> for the Documentation/ABI/ files as well, please redo that in this patch
> series.
Sure.
> But, the bigger question is, why is this a kernel driver at all? Can't
> you do this from userspace today without any new kernel code?
Indeed, it can be done from userspace since we're just controlling
GPIOs. Having a kernel driver allows to describe this device in the
Device Tree, like all other devices, and have it "magically" appear,
with a convenient user-space interface.
Not having a kernel driver means that gazillions of applications
re-invent the same piece of code over and over again, have to hardcode
the GPIO numbers for a given piece of hardware, while the kernel
abstract all of this very nicely.
Thanks,
Thomas
--
Thomas Petazzoni, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com
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