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

On Tue, Feb 01, 2011 at 04:53:44PM +0100, Uwe Kleine-K?nig wrote:

On Tue, Feb 01, 2011 at 03:24:58PM +0000, Russell King - ARM Linux wrote:

quoted

On Tue, Feb 01, 2011 at 04:18:46PM +0100, Uwe Kleine-K?nig wrote:

quoted

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.

So?  You're not _supposed_ to call it from any atomic context ever.