Re: [Outreachy kernel] [PATCH] staging: fbtft: Replace udelay with preferred usleep_range

From: Julia Lawall
Date: Sun Mar 29 2020 - 05:28:37 EST




On Sun, 29 Mar 2020, John B. Wyatt IV wrote:

> Fix style issue with usleep_range being reported as preferred over
> udelay.
>
> Issue reported by checkpatch.
>
> Please review.
>
> As written in Documentation/timers/timers-howto.rst udelay is the
> generally preferred API. hrtimers, as noted in the docs, may be too
> expensive for this short timer.
>
> Are the docs out of date, or, is this a checkpatch issue?
>
> Signed-off-by: John B. Wyatt IV <jbwyatt4@xxxxxxxxx>
> ---
> drivers/staging/fbtft/fb_agm1264k-fl.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/staging/fbtft/fb_agm1264k-fl.c b/drivers/staging/fbtft/fb_agm1264k-fl.c
> index eeeeec97ad27..019c8cce6bab 100644
> --- a/drivers/staging/fbtft/fb_agm1264k-fl.c
> +++ b/drivers/staging/fbtft/fb_agm1264k-fl.c
> @@ -85,7 +85,7 @@ static void reset(struct fbtft_par *par)
> dev_dbg(par->info->device, "%s()\n", __func__);
>
> gpiod_set_value(par->gpio.reset, 0);
> - udelay(20);
> + usleep_range(20, 20);

usleep_range should have a range, eg usleep_range(50, 100);. But it is
hard to know a priori what the range should be. So it is probably better
to leave the code alone.

julia

> gpiod_set_value(par->gpio.reset, 1);
> mdelay(120);
> }
> --
> 2.25.1
>
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