On Wed, Aug 12, 2015 at 09:46:49AM -0700, Michael Turquette wrote:

Quoting Felipe Balbi (2015-08-12 08:02:53)

quoted

On Wed, Aug 12, 2015 at 11:11:51AM +0100, Russell King - ARM Linux wrote:

quoted

On Wed, Aug 12, 2015 at 01:05:58PM +0300, Grygorii Strashko wrote:

quoted

On 08/12/2015 01:06 AM, Michael Turquette wrote:

quoted

Quoting Russell King - ARM Linux (2015-08-11 12:25:15)

quoted

clk_enable/clk_disable _should_ be usable from atomic contexts.

Thanks Russell - above is not true on -RT.

What I'm saying is that it _should_ be true.  You _should_ be able to
call clk_enable()/clk_disable() from atomic contexts.  It's been
documented since forever:

/**
 * clk_enable - inform the system when the clock source should be running.
 * @clk: clock source
 *
 * If the clock can not be enabled/disabled, this should return success.
 *
 * May be called from atomic contexts.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

/**
 * clk_disable - inform the system when the clock source is no longer required.
 * @clk: clock source
 *
 * Inform the system that a clock source is no longer required by
 * a driver and may be shut down.
 *
 * May be called from atomic contexts.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

If that's not true with CCF, that's a CCF bug, not a usage bug.

in that case, CCF's clock need to be converted to raw_spin_locks, that's
the only way to prevent its locks from being reimplemented as rt
mutexes.

I do not keep up much with rt stuff, so I am going to ask a naive
question: is it common to simply do s/spin_lock/raw_spin_lock/g for
driver subsystems when using rt? Sounds like that is all that is
required...

depends, if you want to guarantee your code isn't preemptable, then
yeah.

-- 
balbi