Re: Interrupt issue in twl4030_keypad

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On Mon, Dec 12, 2011 at 9:23 PM, Greg KH <gregkh@xxxxxxx> wrote:
> 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 think you need to tell me exactly what git commit ids in Linus's tree
> that you want to see in the stable kernel releases, which you didn't do
> here :(

All right, I guess that rules out the revert option.

Once Linus merges the latest fixes I can send you the commit ids, and
they will work for 3.1, but I'm not sure for all the other versions
since 2.6.33. The surest thing would be to just revert the patch I
mentioned, which is a relatively small change compared to picking all
those commits.

> Also, please use stable@xxxxxxxxxxxxxxx, stable@xxxxxxxxxx has been dead
> since August.

Ok.

-- 
Felipe Contreras
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