Re: [Outreachy kernel] [PATCH] staging: nvec: cleanup USLEEP_RANGE checkpatch checks

From: Julia Lawall
Date: Thu Mar 02 2017 - 11:52:08 EST




On Thu, 2 Mar 2017, SIMRAN SINGHAL wrote:

>
>
> On Thursday, March 2, 2017 at 8:31:23 PM UTC+5:30, Julia Lawall wrote:
>
>
> On Thu, 2 Mar 2017, SIMRAN SINGHAL wrote:
>
> >
> >
> > On Thursday, March 2, 2017 at 8:06:40 PM UTC+5:30, Julia
> Lawall wrote:
> >
> >
> >       On Thu, 2 Mar 2017, simran singhal wrote:
> >
> >       > Resolve strict checkpatch USLEEP_RANGE checks by
> converting
> >       delays and
> >       > sleeps as described in
> >       ./Documentation/timers/timers-howto.txt.
> >       >
> >       > CHECK: usleep_range is preferred over udelay; see
> >       Documentation/
> >       > timers/timers-howto.txt
> >       >
> >       > Signed-off-by: simran singhal <singhal...@xxxxxxxxx>
> >       > ---
> >       >  drivers/staging/nvec/nvec.c | 4 ++--
> >       >  1 file changed, 2 insertions(+), 2 deletions(-)
> >       >
> >       > diff --git a/drivers/staging/nvec/nvec.c
> >       b/drivers/staging/nvec/nvec.c
> >       > index c1feccf..cd35e64 100644
> >       > --- a/drivers/staging/nvec/nvec.c
> >       > +++ b/drivers/staging/nvec/nvec.c
> >       > @@ -631,7 +631,7 @@ static irqreturn_t
> nvec_interrupt(int irq,
> >       void *dev)
> >       >                  break;
> >       >          case 2:                /* first byte after
> command */
> >       >                  if (status == (I2C_SL_IRQ | RNW |
> RCVD)) {
> >       > -                        udelay(33);
> >       > +                        usleep_range(33, 100);
> >
> >       How did you choose the upper limit.
> >
> >       I believe that Greg previously suggested not to make
> these
> >       changes if you
> >       have no way to test them.
> >
> > Julia, After going through the reply given by Nicholas Mc
> Guire 
> >
> https://www.mail-archive.com/kernelnewbies@xxxxxxxxxxxxxxxxx/msg16464.html
> > in this reply he has mentioned that even the range of 10
> microsecond is
> > enough,
> > so I prefer to take 100 as upper limit.  
>
> Than you for the link.
>
> It looks like he suggests to change 33 to 30-40, not to 33-100.
>  In any
> case, you have three choices for this kind of issue:
> 1. Don't make the change, because you can't test the result
> 2. Make the change, and explain the commit log what your
> rationale is
> 3. Make the change, and explain below the --- that you have no
> idea what
> you are doing, and you are just proposing the patch as something
> concrete
> to start a discussion.
>
> But your preference is not a suitable justification.  The
> hardware does
> something, and the choice can only really be made by the person
> who knows
> what it does.
>
>  
> Thanks, 
> Julia I'll keep this in mind from next time.
>
> I choose the range from 33 to 100 for being on more safer side.
> Should I make it 30-40 and send v2.

I thought that the maintainer already responded saying that one shouldnot
change this code?

julia

>
> julia
>
> >  
> > Simran
> >
> >       julia
> >
> >
> >       >                          if (nvec->rx->data[0] !=
> 0x01) {
> >       >                                  dev_err(nvec->dev,
> >       >                                          "Read without
> prior
> >       read command\n");
> >       > @@ -718,7 +718,7 @@ static irqreturn_t
> nvec_interrupt(int irq,
> >       void *dev)
> >       >           * We experience less incomplete messages
> with this
> >       delay than without
> >       >           * it, but we don't know why. Help is
> appreciated.
> >       >           */
> >       > -        udelay(100);
> >       > +        usleep_range(100, 200);
> >       >
> >       >          return IRQ_HANDLED;
> >       >  }
> >       > --
> >       > 2.7.4
> >       >
> >       > --
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