Re: [PATCH v2 1/2] Input: Add device_enable handler to DaVinci Keyscan platform data

Dmitry Torokhov [off-list ref] writes:

On Mon, Dec 07, 2009 at 04:24:59PM -0800, Kevin Hilman wrote:

quoted

[off-list ref] writes:

quoted

From: Miguel Aguilar <redacted>

Add a function pointer in the platform data of the DaVinci Keyscan driver
called device_enabled, in order to perform board specific actions when
the device is initialized, like setup the PINMUX configuration.

Signed-off-by: Miguel Aguilar <redacted>

Signed-off-by: Kevin Hilman <redacted>

Dmitry,

Will you be queueing this driver (and this patch) for 2.6.34?  I
thought you had accepted the original driver, but I don't see it in
the master or next branch of your input tree at:

  git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input.git

The driver is there, commit bc09dcadc1a3da87d58aa70ebc8e9441205be75c on
'next' branch (I don't really use master branch).  It was committed back
in October, probably that's why you don't see it?

As far as the patch goes - I got an impression from email sent by
Steve that there are ways to do automatic PINMUX detection and thus
this patch was not needed.  Is this ture?

The method Steve was referring to was done for MontaVista
internal/product kernels but was rejected for upstream (by me) because
of the way it was implemented (by tying mux settings to clock
settings.)

If not I am stull unsure what happens if you unload the driver. How
do you restore the old configuration so that the device you took
over from can start working again? Maybe pinmux should be controlled
via sysfs attribute (in board code) so that user can switch on-fly
between the devices?

The way we currently handle MUXing in davinci, you don't need to do
anything after the driver unloads.  Any other user of these pins will
mux them as needed.

If really necessary, we could do an equivalent 'device_disable' hook
but there would be empty as it wouldn't be needed.

So, speaking as maintainer of the DaVinci support, I'm in favor of this
approach from Miguel.

Thanks,


Kevin