linux-kernel - Re: [PATCH v2] staging: rts5208: Replace instances of udelay by usleep

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Date:   Tue, 18 Oct 2022 10:26:03 -0700
From:   Alison Schofield <alison.schofield@...el.com>
To:     Tanjuate Brunostar <tanjubrunostar0@...il.com>
Cc:     gregkh@...uxfoundation.org, linux-staging@...ts.linux.dev,
        linux-kernel@...r.kernel.org, outreachy@...ts.linux.dev
Subject: Re: [PATCH v2] staging: rts5208: Replace instances of udelay by
 usleep_range

On Tue, Oct 18, 2022 at 04:04:02PM +0000, Tanjuate Brunostar wrote:
> Replace the use of udelay by usleep_range as suggested by checkpatch:
> 
> CHECK: usleep_range is preferred over udelay; see Documentation/timers/timers-howto.rst
> +               udelay(30);
> 
> CHECK: usleep_range is preferred over udelay; see Documentation/timers/timers-howto.rst
> +               udelay(50);
> 

Hi Tanjuate,

I'd expect the commit log here to tell me why this is preferable, and
why this is safe to do - basically your summary of what you found
when you considered the checkpatch error report and then read
timers-howto.rst.  Including that this was found my Checkpatch is
good, but that's basically a footnote to the log message, not the
main point.

Having said all that, I see GregKH response and that is typical
for this change. This type of change, needs to be actually tested,
so it's not a good cleanup unless you have the device or some other 
convincing proof that what you are doing is safe.

Outreachy advice:  when you see a checkpatch error, and are
wondering how its fix will be received, search the Outreachy
mail archive for it. This one, I find repeated instances of
the change being NAK'd because the submitter cannot test it.

Alison

> Signed-off-by: Tanjuate Brunostar <tanjubrunostar0@...il.com>
> ---
> 
> v2: changed the max values of the usleep_rage instances as they cannot
> be equal to the min values as suggested by checkpatch
> 
>  drivers/staging/rts5208/ms.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/staging/rts5208/ms.c b/drivers/staging/rts5208/ms.c
> index 14449f8afad5..a9724ca5eccf 100644
> --- a/drivers/staging/rts5208/ms.c
> +++ b/drivers/staging/rts5208/ms.c
> @@ -3235,7 +3235,7 @@ static int ms_write_multiple_pages(struct rtsx_chip *chip, u16 old_blk,
>  			return STATUS_FAIL;
>  		}
>  
> -		udelay(30);
> +		usleep_range(30, 31);
>  
>  		rtsx_init_cmd(chip);
>  
> @@ -4157,7 +4157,7 @@ int mg_set_ICV(struct scsi_cmnd *srb, struct rtsx_chip *chip)
>  
>  #ifdef MG_SET_ICV_SLOW
>  	for (i = 0; i < 2; i++) {
> -		udelay(50);
> +		usleep_range(50, 51);
>  
>  		rtsx_init_cmd(chip);
>  
> -- 
> 2.34.1
> 
>