Re: Locking in the clk API, part 2: clk_prepare/clk_unprepare

[Uwe Kleine-König]

On Tue, Feb 01, 2011 at 03:24:58PM +0000, Russell King - ARM Linux wrote:
> On Tue, Feb 01, 2011 at 04:18:46PM +0100, Uwe Kleine-König wrote:
> > yeah, didn't thought about multiple consumers, so (as Jeremy suggested)
> > the right thing is to sleep until CLK_BUSY is cleared.
> 
> 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;
> }
But you cannot call this in atomic context when you know the clock is
already prepared.

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |
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