linux-kernel - Re: [PATCH] staging: fbtft: replace udelay with usleep

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Date:   Sun, 10 Jul 2022 16:00:19 +0300
From:   Christos Kollintzas <c.kollintzas.92@...il.com>
To:     Greg KH <gregkh@...uxfoundation.org>
Cc:     dri-devel@...ts.freedesktop.org, linux-fbdev@...r.kernel.org,
        linux-staging@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] staging: fbtft: replace udelay with usleep_range

On Sat, Jul 09, 2022 at 12:30:51PM +0200, Greg KH wrote:
> On Sat, Jul 09, 2022 at 01:06:56PM +0300, Christos Kollintzas wrote:
> > Adhere to Linux kernel coding style.
> > 
> > Reported by checkpatch:
> > 
> > CHECK: usleep_range is preferred over udelay
> > 
> > Signed-off-by: Christos Kollintzas <c.kollintzas.92@...il.com>
> > ---
> >  drivers/staging/fbtft/fb_upd161704.c | 18 +++++++++---------
> >  1 file changed, 9 insertions(+), 9 deletions(-)
> > 
> > diff --git a/drivers/staging/fbtft/fb_upd161704.c b/drivers/staging/fbtft/fb_upd161704.c
> > index c680160d6380..eeafbab4ace1 100644
> > --- a/drivers/staging/fbtft/fb_upd161704.c
> > +++ b/drivers/staging/fbtft/fb_upd161704.c
> > @@ -32,27 +32,27 @@ static int init_display(struct fbtft_par *par)
> >  
> >  	/* oscillator start */
> >  	write_reg(par, 0x003A, 0x0001);	/*Oscillator 0: stop, 1: operation */
> > -	udelay(100);
> > +	usleep_range(100, 110);
> 
> When doing these types of changes, you really need access to the
> hardware involved in order to be able to properly test it.
> 
> Especially for this type of function which is trying to do timing
> changes which the hardware requires.
> 
> Did you test this on the real hardware and did it work properly?
> 
> thanks,
> 
> greg k-h

I did not.

I will try to find the hardware and send a patch that is
properly tested.

thanks,

Christos Kollintzas