[PATCH RFC] clk: ux500: add range to usleep_range

[PATCH RFC] clk: ux500: add range to usleep_range

[Nicholas Mc Guire]

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@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);
 
 	return ret;
 }
-- 
2.1.4

Re: [PATCH RFC] clk: ux500: add range to usleep_range

[Stephen Boyd]

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@opentech.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.

Re: [PATCH RFC] clk: ux500: add range to usleep_range

[Nicholas Mc Guire]

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@opentech.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. 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 

Re: [PATCH RFC] clk: ux500: add range to usleep_range

[Ulf Hansson]

On Sun, 7 Apr 2019 at 05:13, 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.
>
> Signed-off-by: Nicholas Mc Guire <hofrat@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));

Kind regards
Uffe

Re: [PATCH RFC] clk: ux500: add range to usleep_range

[Nicholas Mc Guire]

On Thu, Apr 11, 2019 at 11:36:45AM +0200, Ulf Hansson wrote:
> On Sun, 7 Apr 2019 at 05:13, 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.
> >
> > Signed-off-by: Nicholas Mc Guire <hofrat@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 

Re: [PATCH RFC] clk: ux500: add range to usleep_range

[Joe Perches]

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@opentech.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

> 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 

Re: [PATCH RFC] clk: ux500: add range to usleep_range

[Nicholas Mc Guire]

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@opentech.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@debian:~/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 
> 

Re: [PATCH RFC] clk: ux500: add range to usleep_range

[Joe Perches]

On Thu, 2019-04-11 at 14:59 +0200, Nicholas Mc Guire wrote:
> 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@opentech.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@debian:~/git/linux-next$ grep -re '.*\*\s*10.*;$' * | grep -oh '\*\s*10' | sort | uniq -c | sort -nr | more 
>    8568 * 10
>     860 *10

The ratio is about the same in any case.

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

Because the style is not mentioned in coding style.
checkpatch flags it only when using the --strict option

Re: [PATCH RFC] clk: ux500: add range to usleep_range

[Nicholas Mc Guire]

On Thu, Apr 11, 2019 at 06:12:49AM -0700, Joe Perches wrote:
> On Thu, 2019-04-11 at 14:59 +0200, Nicholas Mc Guire wrote:
> > 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@opentech.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@debian:~/git/linux-next$ grep -re '.*\*\s*10.*;$' * | grep -oh '\*\s*10' | sort | uniq -c | sort -nr | more 
> >    8568 * 10
> >     860 *10
> 
> The ratio is about the same in any case.
> 
> > Anyway - is there a reason checkpatch will not flag this ?
> 
> Because the style is not mentioned in coding style.
> checkpatch flags it only when using the --strict option
>
hmm...It sees it is:

3.1) Spaces
***********
...

Use one space around (on each side of) most binary and ternary operators,
such as any of these::

        =  +  -  <  >  *  /  %  |  &  ^  <=  >=  ==  !=  ?  :

thx!
hofrat