Re: [Outreachy kernel] [PATCH] Staging: fbtft: Replace udelay to usleep_range

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Sun, Mar 03, 2019 at 01:59:02PM +0530, Bhagyashri Dighole wrote:
> Replace udelay to usleep_range function call with 10 microsecond range.
> Detected by checkpatch.pl "CHECK: usleep_range is preferred over udelay".
> 
> Signed-off-by: Bhagyashri Dighole <digholebhagyashri@gmail.com>
> ---
>  drivers/staging/fbtft/fb_agm1264k-fl.c |  2 +-
>  drivers/staging/fbtft/fb_ra8875.c      |  4 ++--
>  drivers/staging/fbtft/fb_tinylcd.c     |  2 +-
>  drivers/staging/fbtft/fb_upd161704.c   | 18 +++++++++---------
>  drivers/staging/fbtft/fb_watterott.c   |  4 ++--
>  5 files changed, 15 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/staging/fbtft/fb_agm1264k-fl.c b/drivers/staging/fbtft/fb_agm1264k-fl.c
> index 8f27bd8..b2d19b1 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, 30);

How do you know that 30 is an acceptable value here?

Making this kind of change is tricky if you do not have the hardware
involved, as you are changing the functionality of the driver.  Look up
why checkpatch is asking you to make this change, perhaps that reason is
not relevant for these devices?

I can't take this type of change without testing on the hardware itself,
sorry.

greg k-h