On Mon, Jul 30, 2012 at 4:02 PM, Russell King - ARM Linux
[off-list ref] wrote:

On Mon, Jul 30, 2012 at 03:42:13PM -0700, Turquette, Mike wrote:

quoted

On Mon, Jul 30, 2012 at 3:31 PM, Paul Walmsley [off-list ref] wrote:

quoted

So if we make a change like this one, it seems like we would basically
expect it to break once we start doing anything meaningful with
clk_prepare(), like using clk_prepare() for voltage scaling or something
that requires I2C?  We'd also probably want to mark this with some kind of
"HACK" comment.

Hi Paul,

Did you have anything in mind to start using clk_prepare?  I still
hope to get rid of it some day and replace that call with a
combination of clk_enable and a check like clk_enable_can_sleep.

Don't you dare.

We arrived at the clk_prepare()/clk_enable() split after lots of
discussion between different platform maintainers and their
requirements.

Shoving crap like "clk_enable_can_sleep()" down into drivers is
totally and utterly idiotic.  We've had the situation *already*
where some drivers can be used on some platforms but not on others
because of differences in clk_enable() expectations.

How does having a dynamic run-time check cause a generic driver to run
on "some platforms but not on others"?

Don't go back there.  clk_prepare() and clk_enable() are separate
calls for a very good reason.  One is sleepable, the other can be
called from any atomic contexts.

Two calls exist because of context differences.  But in practice they
do the same thing: cause a line to toggle at a rate.  If a run-time
check exists and the framework could handle this gracefully, why would
you still choose the split api?

Regards,
Mike