Locking in the clk API

[Saravana Kannan]

On 01/22/2011 01:15 AM, Russell King - ARM Linux wrote:
> On Fri, Jan 21, 2011 at 05:53:43PM -0800, Saravana Kannan wrote:
>> On 01/21/2011 01:32 AM, Russell King - ARM Linux wrote:
>>> On Thu, Jan 20, 2011 at 08:12:45PM -0800, Saravana Kannan wrote:
>>>> In my opinion, the only major reason for needing atomic clk APIs was due
>>>> to device_ops->suspend being atomic. Since that's not the case anymore,
>>>> I really don't see a justification for atomic clocks. Sure, I might have
>>>> missed some exceptions, but in that case we should make the atomic APIs
>>>> an exception (add clk_enable_atomic) and not the norm.
>>>
>>> The suspend method has never been atomic.  It has always been able to
>>> sleep.  You're mistaken.
>>
>> I distinctly remember trying to do sleeping stuff inside a .suspend
>> function and have it complain that it's atomic. So, I think you might be
>> mistaken.
>
> No I'm not.  I've always had stuff which takes mutexes/semaphores in
> the suspend method.
>
> You'll get the warning if you take a spinlock and then try sleeping -
> but that's your error for creating an atomic context (you can't sleep
> while holding a spinlock), not the fault of the callback.

I'm well aware of the fact that you can't grab a mutex inside a 
spinlock. Like I said, I will dig into this sometime and get back.

-Saravana

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