The core does not need to hold enable lock for clk_is_enabled API. Update the doc to reflect it. Cc: Jonathan Corbet <corbet@xxxxxxx> Cc: Stephen Boyd <sboyd@xxxxxxxxxxxxxx> Suggested-by: Stephen Boyd <sboyd@xxxxxxxxxxxxxx> Signed-off-by: Dong Aisheng <aisheng.dong@xxxxxxx> --- Documentation/clk.txt | 14 +++++++++++--- 1 file changed, 11 insertions(+), 3 deletions(-) diff --git a/Documentation/clk.txt b/Documentation/clk.txt index be909ed..f286ff5 100644 --- a/Documentation/clk.txt +++ b/Documentation/clk.txt @@ -268,9 +268,17 @@ The common clock framework uses two global locks, the prepare lock and the enable lock. The enable lock is a spinlock and is held across calls to the .enable, -.disable and .is_enabled operations. Those operations are thus not allowed to -sleep, and calls to the clk_enable(), clk_disable() and clk_is_enabled() API -functions are allowed in atomic context. +.disable operations. Those operations are thus not allowed to sleep, +and calls to the clk_enable(), clk_disable() API functions are allowed in +atomic context. + +For clk_is_enabled() API, it is also designed to be allowed to be used in +atomic context. However, it doesn't really make any sense to hold the enable +lock in core, unless you want to do something else with the information of +the enable state with that lock held. Otherwise, seeing if a clk is enabled is +a one-shot read of the enabled state, which could just as easily change after +the function returns because the lock is released. Thus driver onwer needs +judge and take care of it in their driver if it needs lock. The prepare lock is a mutex and is held across calls to all other operations. All those operations are allowed to sleep, and calls to the corresponding API -- 2.7.4 -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
