| Message ID | 1554980651-54136-1-git-send-email-hofrat@opentech.at (mailing list archive) |
|---|---|
| State | Accepted, archived |
| Headers | show |
| Series | [V2] clk: ux500: add range to usleep_range | expand |
On Thu, 11 Apr 2019 at 13:04, Nicholas Mc Guire <hofrat@opentech.at> wrote: > > Providing a range for usleep_range() allows the hrtimer subsystem to > coalesce timers - the delay is runtime configurable so a factor 2 > is taken to provide the range. With the expected range for > enable_delay_us being milliseconds, the range should lie in the 250us > range which is sufficient for hrtimer optimization. > > Signed-off-by: Nicholas Mc Guire <hofrat@opentech.at> Acked-by: Ulf Hansson <ulf.hansson@linaro.org> Kind regards Uffe > --- > > Problem located with an experimental coccinelle script > V2: As clarified by Ulf Hansson <ulf.hansson@linaro.org> the delays > here are typically in the millisecond range - so as proposed > replace the factor 2 by a 25% increase of max. > > Patch was compile tested with: u8500_defconfig (implies COMMON_CLK=y) > (with some unrelated sparse warnings about not implemented system calls) > Patch is against 5.1-rc4 (localversion-next is next=20190410) > > drivers/clk/ux500/clk-sysctrl.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/clk/ux500/clk-sysctrl.c b/drivers/clk/ux500/clk-sysctrl.c > index 7c0403b..698306f 100644 > --- a/drivers/clk/ux500/clk-sysctrl.c > +++ b/drivers/clk/ux500/clk-sysctrl.c > @@ -42,7 +42,8 @@ static int clk_sysctrl_prepare(struct clk_hw *hw) > clk->reg_bits[0]); > > if (!ret && clk->enable_delay_us) > - usleep_range(clk->enable_delay_us, clk->enable_delay_us); > + usleep_range(clk->enable_delay_us, clk->enable_delay_us + > + (clk->enable_delay_us >> 2)); > > return ret; > } > -- > 2.1.4 >
Quoting Nicholas Mc Guire (2019-04-11 04:04:11) > Providing a range for usleep_range() allows the hrtimer subsystem to > coalesce timers - the delay is runtime configurable so a factor 2 > is taken to provide the range. With the expected range for > enable_delay_us being milliseconds, the range should lie in the 250us > range which is sufficient for hrtimer optimization. > > Signed-off-by: Nicholas Mc Guire <hofrat@opentech.at> > --- Applied to clk-next
diff --git a/drivers/clk/ux500/clk-sysctrl.c b/drivers/clk/ux500/clk-sysctrl.c index 7c0403b..698306f 100644 --- a/drivers/clk/ux500/clk-sysctrl.c +++ b/drivers/clk/ux500/clk-sysctrl.c @@ -42,7 +42,8 @@ static int clk_sysctrl_prepare(struct clk_hw *hw) clk->reg_bits[0]); if (!ret && clk->enable_delay_us) - usleep_range(clk->enable_delay_us, clk->enable_delay_us); + usleep_range(clk->enable_delay_us, clk->enable_delay_us + + (clk->enable_delay_us >> 2)); return ret; }
Providing a range for usleep_range() allows the hrtimer subsystem to coalesce timers - the delay is runtime configurable so a factor 2 is taken to provide the range. With the expected range for enable_delay_us being milliseconds, the range should lie in the 250us range which is sufficient for hrtimer optimization. Signed-off-by: Nicholas Mc Guire <hofrat@opentech.at> --- Problem located with an experimental coccinelle script V2: As clarified by Ulf Hansson <ulf.hansson@linaro.org> the delays here are typically in the millisecond range - so as proposed replace the factor 2 by a 25% increase of max. Patch was compile tested with: u8500_defconfig (implies COMMON_CLK=y) (with some unrelated sparse warnings about not implemented system calls) Patch is against 5.1-rc4 (localversion-next is next=20190410) drivers/clk/ux500/clk-sysctrl.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)