On Tue, Dec 26, 2017 at 05:29:18PM -0800, Stephen Boyd wrote: > 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. >
Yes, you're absolutely right. I could draft a patch to update it later. Thanks Regards Dong Aisheng > -- > Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, > a Linux Foundation Collaborative Project > -- > To unsubscribe from this list: send the line "unsubscribe linux-clk" in > the body of a message to [email protected] > More majordomo info at http://vger.kernel.org/majordomo-info.html
