linux-kernel - Re: [PATCH RFC] clk: ux500: add range to usleep

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Date:   Thu, 11 Apr 2019 14:59:18 +0200
From:   Nicholas Mc Guire <der.herr@...r.at>
To:     Joe Perches <joe@...ches.com>
Cc:     Stephen Boyd <sboyd@...nel.org>,
        Nicholas Mc Guire <hofrat@...ntech.at>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Michael Turquette <mturquette@...libre.com>,
        linux-arm-kernel@...ts.infradead.org, linux-clk@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH RFC] clk: ux500: add range to usleep_range

On Thu, Apr 11, 2019 at 04:51:25AM -0700, Joe Perches wrote:
> On Thu, 2019-04-11 at 04:56 +0200, Nicholas Mc Guire wrote:
> > On Wed, Apr 10, 2019 at 03:53:51PM -0700, Stephen Boyd wrote:
> > > Quoting Nicholas Mc Guire (2019-04-06 20:13:24)
> > > > 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 <hofrat@...ntech.at>
> > > > ---
> > > 
> > > I think this driver is in maintenance mode. I'll wait for Ulf to ack or
> > > review this change before applying.
> > > 
> > > > 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);
> > > 
> > > Please add space around that multiply.
> > > 
> > I can do that but it does not seem common and also checkpatch
> > did not complain about this - now a simple grep -re "\*10" on the
> > kernel shows that it seems more common not to use spaces around *
> > that to use them.
> 
> Not really
> 
> $ git grep -P '\*\s*10' | grep -oh -P '\*\s*10' | \
>   sort | uniq -c | sort -rn | head 
>   11800 * 10
>    1705 *10
>     179 *  10
>      74 *   10
>      67 *	10
>      20 *     10
>      20 *      10
>      14 *    10
>      14 *		10
>      12 *         10

yup - my bad - If you restrict it to code lines - its 1:10
not quite sure how I got the first numbers - sloppy check.

hofrat@...ian:~/git/linux-next$ grep -re '.*\*\s*10.*;$' * | grep -oh '\*\s*10' | sort | uniq -c | sort -nr | more 
   8568 * 10
    860 *10

Anyway - is there a reason checkpatch will not flag this ?

thx!
hofrat

> 
> > Greping specifically for cases using usleep_range()
> > (not that many) it seems more or less evenly devided between space
> > and no space - so the concern is overlooking that factor 2 ?
> > 
> > thx!
> > hofrat 
>