linux-kernel - Re: [PATCH] FBTFT: fb_agm1264k: usleep

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Date:   Mon, 9 Sep 2019 10:56:25 +0100
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Sreeram Veluthakkal <srrmvlt@...il.com>
Cc:     devel@...verdev.osuosl.org, linux-fbdev@...r.kernel.org,
        nishadkamdar@...il.com, linux-kernel@...r.kernel.org,
        dri-devel@...ts.freedesktop.org, payal.s.kshirsagar.98@...il.com
Subject: Re: [PATCH] FBTFT: fb_agm1264k: usleep_range is preferred over udelay

On Sun, Sep 08, 2019 at 08:26:05PM -0500, Sreeram Veluthakkal wrote:
> This patch fixes the issue:
> FILE: drivers/staging/fbtft/fb_agm1264k-fl.c:88:
> CHECK: usleep_range is preferred over udelay; see Documentation/timers/timers-howto.rst
> +       udelay(20);
> 
> Signed-off-by: Sreeram Veluthakkal <srrmvlt@...il.com>
> ---
>  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..2dece71fd3b5 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, 40);

Is it "safe" to wait 40?  This kind of change you can only do if you
know this is correct.  Have you tested this with hardware?

thanks,

greg k-h