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

From: Archit Taneja
Date: Thu Sep 07 2017 - 01:30:04 EST


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@xxxxxx>
Tested-by: Philippe Cornu <philippe.cornu@xxxxxx>
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
---
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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