Re: OMAP baseline test results for v3.7-rc2

[Kevin Hilman <khilman@deeprootsystems.com>]

Kevin Hilman <khilman@deeprootsystems.com> writes:

> +Igor
>
> Paul Walmsley <paul@pwsan.com> writes:
>
>> Here are some basic OMAP test results for Linux v3.7-rc2.
>> Logs and other details at:
>>
>>     http://www.pwsan.com/omap/testlogs/test_v3.7-rc2/20121020134755/
>
> [...]
>
>> * 37xx EVM: CORE not entering dynamic off-idle
>>   - Cause unknown; dynamic retention-idle seems to work; system suspend to 
>>     off works
>
> I got a start on this one, and discovered (using CM_IDLEST1_CORE) that
> SPI1 was not idle when going off.  A quick hack disabling the
> touchscreen showed that after that, core was hitting idle just fine.
>
> I ran out of time today debugging this, but it's definitely realted to
> the GPIO debounce setting for the touchscreen.  Changing it to zero[1]
> makes CORE hit retention again in idle.

OK, found the root cause of this in the GPIO driver.  Patch submitted:

    http://marc.info/?l=linux-omap&m=135101577925972&w=2

however...

> Igor, I'm hoping you might know what's going on here since we already
> had some problems with this ads7846 init stuff and you're more familiar
> with this debounce init.

... board files that are setting debounce values for ads7846 will no
longer work.  

Currently, omap_ads7846_init() in common-board-devices.c does this:

   gpio_request_one()
   gpio_set_debounce()
   gpio_free()                    

because of a bug in the GPIO driver, the debounce settings were sticky
and lingered even after the gpio_free().  That bug has been fixed by the
above patch, which means the above gpio_set_debounce() is completely
pointless because it's followed immediately by a gpio_free().

IMO, the whole GPIO init for the ads7846 needs a rethink as it's
currently partially done by common-board-devices.c and done (again) in
the ads7846 driver.  If the gpio_free() isn't done in
common-board-devices, then the ads7846 driver will currently fail to
probe/load becasue it can't request a GPIO line.

Having found and fixed the PM regression, I'll leave the ads7846 cleanup to
somone else.

Kevin