[RFC,PATCH 1/3] Add a common struct clk

On Thu, Feb 10, 2011 at 11:10:52PM +1300, Ryan Mallon wrote:

On 10/02/11 23:03, Richard Zhao wrote:

quoted

On Thu, Feb 10, 2011 at 09:21:14AM +1300, Ryan Mallon wrote:

quoted

On 02/09/2011 07:41 PM, Jeremy Kerr wrote:

Hi Jeremy,

Couple more comments below.

~Ryan

[...]

quoted

quoted

+int clk_enable(struct clk *clk)
+{
+     unsigned long flags;
+     int ret = 0;
+
+     spin_lock_irqsave(&clk->enable_lock, flags);

        WARN_ON(clk->prepare_count == 0); ?

quoted

+     if (clk->enable_count == 0&&  clk->ops->enable)
+             ret = clk->ops->enable(clk);

Does it make sense to have a clock with no enable function which still
returns success from clk_enable? Do we have any platforms which have
NULL clk_enable functions?

I think that for enable/disable at least we should require platforms to
provide functions and oops if they have failed to do so. In the rare
case that a platform doesn't need to do anything for enable/disable they
can just supply empty functions.

It's possible to be NULL. So are set_rate/get_rate.
Ideally, if it's NULL:
prepare/unprepare: only call parent's prepare/unprepare
enable/disable: only call parent's enable/disable

No, the whole point of the generic framework is that _all_ clock
users must call prepare/enable and disable/unprepare. Drivers, etc
should not rely on underlying knowledge of a platform. This is why,
for instance, clk_enable will warn if prepare count is zero.

However, I can see that a clock may be fully enabled by its prepare
function and so the enable function is a no-op. User must still call
both prepare and enable though. Perhaps this is what you meant?

I mean prepare/unprepare, enable/disable and get_rate ops null can be handled
in the common clock code. But it needs parent clock pointer.

Thanks
Richard

~Ryan

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