Re: [PATCH] Lock 7 is cpuidle specific, use non-generic value for locking

[Lina Iyer <lina.iyer@linaro.org>]

On Fri, Mar 13 2015 at 14:02 -0600, Andy Gross wrote:
>On Thu, Mar 12, 2015 at 04:16:00PM -0600, Lina Iyer wrote:
>
><snip>
>
>> >It looks like the remote side unlocks it too? It doesn't seem like this
>> >will work with the framework very well. The framework has a kernel
>> >spinlock attached to the hwspinlock so when we lock the hwspinlock we
>> >also lock the kernel spinlock and we only release the kernel spinlock
>> >when the kernel unlocks the hwspinlock. In this case it seems like
>> >cpuidle wants to have it's own kernel spinlock and just use the trylock
>> >loop part of __hwspin_lock_timeout() without taking any kernel side
>> >locks. Plus it wants to write a specific value to the lock.
>> >
>> Right.
>> Just noticed that part of the hwspinlock. Yes SCM unlocks the
>> hwspinlock. So I cannot hold any lock in Linux. May need changes in the
>> hwspinlock framework. Seems like an additional flag in hwspinlock to not
>> lock any in the trylock path work work. Hmm....
>
>Or a specific EXPORT function for this one usecase which is unlike anyone elses
>usage.

I think, this can be handled well within the QCOM driver. I will submit
a patch for it and we can discuss then later. For now, this will work
fine as is.

Lina

>
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