linux-kernel - Re: [PATCH] [RESEND] drm/stm: fix warning about multiplication in condition

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Message-ID: <20170908063020.ii6txwy3mkzofhi4@phenom.ffwll.local>
Date:   Fri, 8 Sep 2017 08:30:20 +0200
From:   Daniel Vetter <daniel@...ll.ch>
To:     Archit Taneja <architt@...eaurora.org>
Cc:     Arnd Bergmann <arnd@...db.de>,
        Yannick Fertre <yannick.fertre@...com>,
        Philippe Cornu <philippe.cornu@...com>,
        Benjamin Gaignard <benjamin.gaignard@...aro.org>,
        Vincent Abriou <vincent.abriou@...com>,
        David Airlie <airlied@...ux.ie>, linux-kernel@...r.kernel.org,
        dri-devel@...ts.freedesktop.org,
        Neil Armstrong <narmstrong@...libre.com>
Subject: Re: [PATCH] [RESEND] drm/stm: fix warning about multiplication in
 condition

On Thu, Sep 07, 2017 at 10:59:49AM +0530, Archit Taneja wrote:
> Hi Benjamin,
> 
> This should be pushed to drm-misc by you, right?

I applied it. I guess Philippe Cornu should also become drm-misc committer
instead of just acking a patch and hoping fairies will pick it up.
-Daniel

> 
> Thanks,
> Archit
> 
> On 09/06/2017 06:43 PM, Arnd Bergmann wrote:
> > gcc-7 complains about multiplying within a condition being
> > suspicious:
> > 
> > drivers/gpu/drm/stm/dw_mipi_dsi-stm.c: In function 'dsi_pll_get_clkout_khz':
> > drivers/gpu/drm/stm/dw_mipi_dsi-stm.c:117:10: error: '*' in boolean context, suggest '&&' instead [-Werror=int-in-bool-context]
> > 
> > The code here is correct, but can be easily rephrased to make
> > that more obvious. I also swap out the error handling and the normal
> > code path for clarity.
> > 
> > Fixes: b0f09a3c69d9 ("drm/stm: Add STM32 DSI controller driver")
> > Acked-by: Philippe Cornu <philippe.cornu@...com>
> > Tested-by: Philippe Cornu <philippe.cornu@...com>
> > Signed-off-by: Arnd Bergmann <arnd@...db.de>
> > ---
> > Originally sent on July 25, but never made it into linux-next.
> > The warning is currently disabled in mainline, but this seems
> > to be a legitimate instance, and we may want to turn it back
> > on in the future.
> > ---
> >   drivers/gpu/drm/stm/dw_mipi_dsi-stm.c | 8 +++++---
> >   1 file changed, 5 insertions(+), 3 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/stm/dw_mipi_dsi-stm.c b/drivers/gpu/drm/stm/dw_mipi_dsi-stm.c
> > index 568c5d0461ea..e5b6310240fe 100644
> > --- a/drivers/gpu/drm/stm/dw_mipi_dsi-stm.c
> > +++ b/drivers/gpu/drm/stm/dw_mipi_dsi-stm.c
> > @@ -113,11 +113,13 @@ static enum dsi_color dsi_color_from_mipi(enum mipi_dsi_pixel_format fmt)
> >   static int dsi_pll_get_clkout_khz(int clkin_khz, int idf, int ndiv, int odf)
> >   {
> > +	int divisor = idf * odf;
> > +
> >   	/* prevent from division by 0 */
> > -	if (idf * odf)
> > -		return DIV_ROUND_CLOSEST(clkin_khz * ndiv, idf * odf);
> > +	if (!divisor)
> > +		return 0;
> > -	return 0;
> > +	return DIV_ROUND_CLOSEST(clkin_khz * ndiv, divisor);
> >   }
> >   static int dsi_pll_get_params(int clkin_khz, int clkout_khz,
> > 
> 
> -- 
> Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
> a Linux Foundation Collaborative Project
> _______________________________________________
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> dri-devel@...ts.freedesktop.org
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch

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