On Thu, Apr 11, 2019 at 11:36:45AM +0200, Ulf Hansson wrote: > On Sun, 7 Apr 2019 at 05:13, Nicholas Mc Guire <hof...@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. > > > > Signed-off-by: Nicholas Mc Guire <hof...@opentech.at> > > --- > > > > Problem located with an experimental coccinelle script > > > > Q: Basically usleep_range() with min == max never makes much sense notably > > in non-atomic context. If the factor of 2 is tolerable or a fixed > > offset of e.g. 1000 would be more suitable is not clear to me - maybe > > someone familiar with that driver can clarify this. > > > > Patch was compile tested with: u8500_defconfig (implies COMMON_CLK=y) > > (with some sparse warnings about not implemented system calls) > > > > Patch is against 5.1-rc3 (localversion-next is next=20190405) > > > > drivers/clk/ux500/clk-sysctrl.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/drivers/clk/ux500/clk-sysctrl.c > > b/drivers/clk/ux500/clk-sysctrl.c > > index 7c0403b..a1fa3fb 100644 > > --- a/drivers/clk/ux500/clk-sysctrl.c > > +++ b/drivers/clk/ux500/clk-sysctrl.c > > @@ -42,7 +42,7 @@ 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*2); > > The range being used is actually in ms, so not sure we actually need > to double it for the range. > > How about adding ~25% instead, along the lines of below: > usleep_range(clk->enable_delay_us, clk->enable_delay_us + > (clk->enable_delay_us >> 2)); > that would be perfectly sufficient for hrtimers - if the range is in ms - so I´ll send out a V2 shortly.
thx! hofrat
