[U-Boot] [PATCH] mx6: Add IOMUX_CONFIG_SION flag to all GPIO pins

[Eric Nelson <eric.nelson@boundarydevices.com>]

Hi Stefano,

On 10/01/2013 07:49 AM, Stefano Babic wrote:
> Hi Eric,
>
> On 01/10/2013 16:26, Eric Nelson wrote:
>
>> I'm not sure where you're seeing this in the RM, but in
>> order to read the pad state when not configured as an input,
>> the SION bit needs to be set in the pad mux register on i.MX51/53.
>
> I have checked inside the "37.3.2.2 GPIO Write" for i.MX53 and "
> 35.4.2.1 Read Value from Pad" for i:MX51, I have not read anything about
> SION. If someone has found where it is described, please mail !
>

That documentation seems to imply that there's no dependency
(i.e. there's no reference to SION), but I think that's an omission.

>>
>> FWIW, this also works when not muxed as a GPIO, which is really
>> handy for verifying that a PWM is toggling, et cetera.
>
> Well, if you have directly tested it, it is better proofed as by the
> manuals..then we need the same fix for i.MX51/i.MX53, too.
>

I've tested this many times, since it's a really handy way of
debugging hardware setups.

That said, I'm not sure that there's a huge difference between
a single patch or multiple patches for each arch unless there's
some functionality dependent on being able to read the actual
value of a pin configured as a GPIO output.

Did I miss something in this thread that does actually require
that ability? It seems a pretty obscure thing in the normal case
to drive an output without confidence that it will succeed.

Regards,


Eric