Hi Russell,

On 18 July 2018 14:19, Geert Uytterhoeven wrote:

On Wed, Jul 18, 2018 at 3:02 PM Russell King - ARM Linux  wrote:

quoted

On Wed, Jul 18, 2018 at 01:57:38PM +0100, Phil Edworthy wrote:

quoted

Behaves the same as (devm_)clk_get except where there is no clock
producer. In this case, instead of returning -ENOENT, the function
returns NULL. This makes error checking simpler and allows
clk_prepare_enable, etc to be called on the returned reference
without additional checks.

How does this work with non-DT systems, where looking a clock up which
isn't yet registered with clkdev returns -ENOENT ?

(clkdev doesn't know when all clocks are registered with it.)

Good question.

I guess all drivers trying to handle optional clocks this way are already broken
on non-DT systems where clocks may be registered late...

So how do non-DT systems that look a clock up which isn't yet
registered with clkdev, determine that an optional clock is there
or not?

Thanks
Phil