[RESEND] drm/stm: fix warning about multiplication in condition

Submitted by Arnd Bergmann on Sept. 6, 2017, 1:13 p.m.

Details

Message ID 20170906131331.2691300-1-arnd@arndb.de
State New
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Series "drm/stm: fix warning about multiplication in condition" ( rev: 2 ) in DRI devel

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Commit Message

Arnd Bergmann Sept. 6, 2017, 1:13 p.m.
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@st.com>
Tested-by: Philippe Cornu <philippe.cornu@st.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.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(-)

Patch hide | download patch | download mbox

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,

Comments

Hi Benjamin,

This should be pushed to drm-misc by you, right?

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@st.com>
> Tested-by: Philippe Cornu <philippe.cornu@st.com>
> Signed-off-by: Arnd Bergmann <arnd@arndb.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,
>
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@st.com>
> > Tested-by: Philippe Cornu <philippe.cornu@st.com>
> > Signed-off-by: Arnd Bergmann <arnd@arndb.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,
> > 
> 
> -- 
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