linux-kernel - Re: [PATCH 2/2] fbdev: ssd1307fb: check return value while setting offset

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Date:	Tue, 13 Jan 2015 14:39:03 +0100
From:	Maxime Ripard <maxime.ripard@...e-electrons.com>
To:	Prabhakar Lad <prabhakar.csengg@...il.com>
Cc:	Tomi Valkeinen <tomi.valkeinen@...com>,
	LFBDEV <linux-fbdev@...r.kernel.org>,
	Jean-Christophe Plagniol-Villard <plagnioj@...osoft.com>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/2] fbdev: ssd1307fb: check return value while setting
 offset

On Tue, Jan 13, 2015 at 11:53:01AM +0000, Prabhakar Lad wrote:
> On Tue, Jan 13, 2015 at 11:43 AM, Tomi Valkeinen <tomi.valkeinen@...com> wrote:
> > On 08/01/15 10:17, Lad, Prabhakar wrote:
> >> this patch checks the return value of write command while
> >> setting the display offset.
> >>
> >> Signed-off-by: Lad, Prabhakar <prabhakar.csengg@...il.com>
> >> ---
> >>  drivers/video/fbdev/ssd1307fb.c | 2 +-
> >>  1 file changed, 1 insertion(+), 1 deletion(-)
> >>
> >> diff --git a/drivers/video/fbdev/ssd1307fb.c b/drivers/video/fbdev/ssd1307fb.c
> >> index 70e3ce8..a7ecaa6 100644
> >> --- a/drivers/video/fbdev/ssd1307fb.c
> >> +++ b/drivers/video/fbdev/ssd1307fb.c
> >> @@ -342,7 +342,7 @@ static int ssd1307fb_ssd1306_init(struct ssd1307fb_par *par)
> >>
> >>       /* set display offset value */
> >>       ret = ssd1307fb_write_cmd(par->client, SSD1307FB_SET_DISPLAY_OFFSET);
> >> -     ret = ssd1307fb_write_cmd(par->client, 0x20);
> >> +     ret = ret & ssd1307fb_write_cmd(par->client, 0x20);
> >>       if (ret < 0)
> >>               return ret;
> >
> > Hrm, what's that supposed to do? If both calls to ssd1307fb_write_cmd()
> > return an error, they are anded, resulting in a garbage error code...
> >
> Agreed I have just aligned this to rest of the code in this function.
> 
> Maxime if you are OK I'll post a patch returning error then and there ?

I'm not sure what the question is, but Tomi is right, having two
returns seems the right thing to do.

Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

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