Re: [PATCH] gpio/omap: fix wakeups on level-triggered GPIOs

[Kevin Hilman <khilman@ti.com>]

Hi Tarun,

"DebBarma, Tarun Kanti" <tarun.kanti@ti.com> writes:

> On Wed, Feb 22, 2012 at 12:31 AM, Kevin Hilman <khilman@ti.com> wrote:
>> While both level- and edge-triggered GPIOs are capable of generating
>> interrupts, only edge-triggered GPIOs are capable of generating a
>> module-level wakeup to the PRCM (c.f. 34xx NDA TRM section 25.5.3.2.)
>>
>> In order to ensure that devices using level-triggered GPIOs as
>> interrupts can also cause wakeups (e.g. from idle), this patch enables
>> edge-triggering for wakeup-enabled, level-triggered GPIOs when a GPIO
>> bank is runtime-suspended (which also happens during idle.)
>>
>> This fixes a problem found in GPMC-connected network cards with GPIO
>> interrupts (e.g. smsc911x on Zoom3, Overo, ...) where network booting
>> with NFSroot was very slow since the GPIO IRQs used by the NIC were
>> not generating PRCM wakeups, and thus not waking the system from idle.
>> NOTE: until v3.3, this boot-time problem was somewhat masked because
>> the UART init prevented WFI during boot until the full serial driver
>> was available.  Preventing WFI allowed regular GPIO interrupts to fire
>> and this problem was not seen.  After the UART runtime PM cleanups, we
>> no longer avoid WFI during boot, so GPIO IRQs that were not causing
>> wakeups resulted in very slow IRQ response times.
>>
>> Tested on platforms using level-triggered GPIOs for network IRQs using
>> the SMSC911x NIC: 3530/Overo and 3630/Zoom3.
>>
>> Reported-by: Tony Lindgren <tony@atomide.com>
>> Signed-off-by: Kevin Hilman <khilman@ti.com>
>
> I have tested on OMAP3430 by making modification to touchscreen GPIO.
> (I had similar change in my next planned cleanup/fix series.)
> If needed you can add my Tested-by:

Thanks for testing, I'll add a Tested-by from you and Tony before
submitting to Grant.

Kevin
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