Re: Interrupt issue in twl4030_keypad

[Felipe Balbi <balbi@ti.com>]

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Hi,

On Mon, Dec 12, 2011 at 08:30:49PM +0200, Felipe Contreras wrote:
> The short version is this: either we revert this patch[1], or we apply
> this patch series[2], as well as its essential fixes[3].
> 
> The long version is this. There's a synchronization issue with the
> current keypad driver and twl core; the irq is marked as handled even
> though the thread that is supposed to handle it hasn't run yet, and
> since it's clear-on-read, and it hasn't been read, it's detected
> again, so they keypad driver receives two interrupt callbacks instead
> of one, and in the second one reads nothing from the i2c register, so
> a key release is assumed. This makes key-presses as simple as shift+a
> impossible.
> 
> In other words, it's totally unreliable. This might not be isolated to
> the keypard driver, but other "nested" interrupts from twl core that
> started using request_threaded_irq prematurely (before it was
> supported by the twl core). But at least I haven't tried those.
> 
> This patch was applied on 2.6.33, which means all versions before 3.2
> are affected, including 3.1.
> 
> What do you think about fixing this on stable kernels?

I believe Samuel has already applied those to the MFD tree. The funny
part is that those patches were pending on linux-omap for over 2 months
I have refreshed them over and over again and asked for help from other
people to test.

Everything went smooth on my simple beagle board with no keypad and I
couldn't see any issues, unfortunately. Still, 2 months is a whole lot
of time to NAK a patch, but nobody said anything so, of course, Samuel
assumed it was ok and, like I said above, it worked for my simple GPIO
usecase with beagleboard.

Oh well, it won't change anything now, Sam has applied Neil's fixes.

-- 
balbi

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