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

[Lina Iyer]

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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> Qualcomm Innovation Center, Inc.
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project
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