[U-Boot] [PATCH 1/2] efikamx: Configure the pins as GPIOs prior to using gpio_get_value.

[Stefano Babic <sbabic@denx.de>]

On 21/11/2011 22:22, Mike Frysinger wrote:

>> Of course ... considering there's always one correct setting for
>> the pin to be in GPIO mode, which I suspect might not be
>> completely true today anymore.
> 
> i find it hard to envision a pinmux system where individual pins
> would have different pinmux configurations to get it into GPIO
> mode.  probably be saner to have gpio_request() do the right thing
> and wait for someone to come forward with the unusual setup --
> worry about it then.

In fact it would be nicer if gpio_request() takes care of the pinmux,
in the way I can see on the davinci SOCs. However, on the IMXs a
single GPIO can be connected (not at the same time, of course) to
different PADs, depending on a general setup (GPR register) or if the
daisy chain in the multiplexer is activated.

Calling gpio_request and passing only the gpio number is not enough on
the IMXs to find where the GPIO is routed.

The second point I will arise is that, mainly due to the different
internal layout but also for historical reasons, the setup and the
provided function for the multiplexer is very different among the SOCs.

Only mx35 and mx5 expone the same interface (mxc_request_iomux), while
mx31/mx25/mx27/mx28 have its own. Because we use and we want to use
the GPIO framework, the gpio driver, common to all IMX SOCs, should be
able to set up the multiplexer independently from the SOC type, that
means we should have the same interface for the multiplexer, and we
have not (yet ?).

Stefano

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