| Message ID | E1Ye58t-0001At-NZ@rmk-PC.arm.linux.org.uk (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Fri, 3 Apr 2015, Russell King wrote: > The idea is that rate = clk_round_rate(clk, r) is equivalent to: > > clk_set_rate(clk, r); > rate = clk_get_rate(clk); > > except that clk_round_rate() does not change the hardware in any way. > > Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk> > --- > include/linux/clk.h | 14 ++++++++++++++ > 1 file changed, 14 insertions(+) > > diff --git a/include/linux/clk.h b/include/linux/clk.h > index 8381bbfbc308..d1ac9f3ab24b 100644 > --- a/include/linux/clk.h > +++ b/include/linux/clk.h > @@ -288,6 +288,20 @@ void devm_clk_put(struct device *dev, struct clk *clk); > * @clk: clock source > * @rate: desired clock rate in Hz > * > + * This answers the question "if I were to pass @rate to clk_set_rate(), > + * what clock rate would I end up with?" without changing the hardware > + * in any way. In other words: > + * > + * rate = clk_round_rate(clk, r); > + * > + * and: > + * > + * clk_set_rate(clk, r); > + * rate = clk_get_rate(clk); > + * > + * are equivalent except the former does not modify the clock hardware > + * in any way. > + * > * Returns rounded clock rate in Hz, or negative errno. > */ > long clk_round_rate(struct clk *clk, unsigned long rate); > -- > 1.8.3.1 Very good. IMHO there should be much more documentation of this type in the kernel. /Ricard
diff --git a/include/linux/clk.h b/include/linux/clk.h index 8381bbfbc308..d1ac9f3ab24b 100644 --- a/include/linux/clk.h +++ b/include/linux/clk.h @@ -288,6 +288,20 @@ void devm_clk_put(struct device *dev, struct clk *clk); * @clk: clock source * @rate: desired clock rate in Hz * + * This answers the question "if I were to pass @rate to clk_set_rate(), + * what clock rate would I end up with?" without changing the hardware + * in any way. In other words: + * + * rate = clk_round_rate(clk, r); + * + * and: + * + * clk_set_rate(clk, r); + * rate = clk_get_rate(clk); + * + * are equivalent except the former does not modify the clock hardware + * in any way. + * * Returns rounded clock rate in Hz, or negative errno. */ long clk_round_rate(struct clk *clk, unsigned long rate);
The idea is that rate = clk_round_rate(clk, r) is equivalent to: clk_set_rate(clk, r); rate = clk_get_rate(clk); except that clk_round_rate() does not change the hardware in any way. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk> --- include/linux/clk.h | 14 ++++++++++++++ 1 file changed, 14 insertions(+)