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 <[email protected]>
---
Problem located with an experimental coccinelle script
V2: As clarified by Ulf Hansson <[email protected]> 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
On Thu, 11 Apr 2019 at 13:04, Nicholas Mc Guire <[email protected]> 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 <[email protected]>
Acked-by: Ulf Hansson <[email protected]>
Kind regards
Uffe
> ---
>
> Problem located with an experimental coccinelle script
> V2: As clarified by Ulf Hansson <[email protected]> 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 <[email protected]>
> ---
Applied to clk-next