Messages in this thread | | | Date | Tue, 01 Feb 2011 12:33:12 -0800 | From | Saravana Kannan <> | Subject | Re: Locking in the clk API, part 2: clk_prepare/clk_unprepare |
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On 02/01/2011 07:24 AM, Russell King - ARM Linux wrote: > A simpler way to write this is: > > int clk_prepare(struct clk *clk) > { > int ret = 0; > > mutex_lock(&clk->mutex); > if (clk->prepared == 0) > ret = clk->ops->prepare(clk); > if (ret == 0) > clk->prepared++; > mutex_unlock(&clk->mutex); > > return ret; > } > > I think we want to take a common mutex not only for clk_prepare(), but > also for clk_set_rate(). If prepare() is waiting for a PLL to lock, > we don't want a set_rate() interfering with that.
Looks like this is the best acknowledgment/response I can expect to get from Russell on this point that I raised.
Jeremy,
When you update the comments/doc to indicate clk_prepare/unprepare is not atomic, can you also update the comment for set_rate() and mark it as non-atomic?
Thanks for starting this thread. My efforts to reignite the other thread didn't go anywhere. Glad to see it's moving forward.
> I'd also be tempted at this stage to build-in a no-op dummy clock, > that being the NULL clk: >[snip] > as we have various platforms defining a dummy struct clk as a way of > satisfying various driver requirements. These dummy clocks are exactly > that - they're complete no-ops.
Unrelated to this thread, but I Ack this request too.
-Saravana
-- Sent by an employee of the Qualcomm Innovation Center, Inc. The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum.
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