On 12/22, Dong Aisheng wrote: > According to design doc, .is_enabled should be protected by enable lock. > Then users don't have to protect it against enable/disable operation > in clock drivers. > > See: Documentation/clk.txt > "The enable lock is a spinlock and is held across calls to the .enable, > .disable and .is_enabled operations." > > Cc: Stephen Boyd <[email protected]> > Cc: Michael Turquette <[email protected]> > Signed-off-by: Dong Aisheng <[email protected]> > --- > drivers/clk/clk.c | 9 ++++++++- > 1 file changed, 8 insertions(+), 1 deletion(-) > > diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c > index e24968f..d6e2d5c 100644 > --- a/drivers/clk/clk.c > +++ b/drivers/clk/clk.c > @@ -198,14 +198,19 @@ static bool clk_core_is_prepared(struct clk_core *core) > > static bool clk_core_is_enabled(struct clk_core *core) > { > + unsigned long flags; > bool ret = false; > > + flags = clk_enable_lock(); > + > /* > * .is_enabled is only mandatory for clocks that gate > * fall back to software usage counter if .is_enabled is missing > */ > - if (!core->ops->is_enabled) > + if (!core->ops->is_enabled) { > + clk_enable_unlock(flags); > return core->enable_count; > + } > > /* > * Check if clock controller's device is runtime active before > @@ -230,6 +235,8 @@ static bool clk_core_is_enabled(struct clk_core *core) > if (core->dev) > pm_runtime_put(core->dev); > > + clk_enable_unlock(flags); > + > return ret; > }
It doesn't really make any sense to hold the enable lock inside the clk_core_is_enabled() function, 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. We should update the documentation. -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project
