Messages in this thread Patch in this message | | | From | Karol Herbst <> | Date | Wed, 6 Sep 2017 16:20:59 +0200 | Subject | Re: [Nouveau] [PATCH] [RESEND] drm/nouveau/clk: fix gcc-7 -Wint-in-bool-context warning |
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On Wed, Sep 6, 2017 at 3:56 PM, Arnd Bergmann <arnd@arndb.de> wrote: > gcc thinks that interpreting a multiplication result as a bool > is confusing: > > drivers/gpu/drm/nouveau/nvkm/subdev/clk/gt215.c: In function 'read_pll': > drivers/gpu/drm/nouveau/nvkm/subdev/clk/gt215.c:133:8: error: '*' in boolean context, suggest '&&' instead [-Werror=int-in-bool-context] > > In this instance, I think using multiplication is more intuitive > than '&&', so I'm adding a comparison to zero instead to shut up > the warning. To further improve readability, I also make the > error case indented and leave the normal case as the final 'return' > statement. >
I think to make perfectly clear why this check is done, we simply should precompute the denominator and do something like this:
int denominator = M * P if (denominator == 0) return 0; return sclk * N / denominator;
but with a better name for "denominator". I even imagine, that there are some macros in the kernel for dealing with something like this already, so that we could do instead:
return AWESOME_DIV_MACRO(sclk * N, M * P)
> Fixes: 7632b30e4b8b ("drm/nouveau/clk: namespace + nvidia gpu names (no binary change)") > Signed-off-by: Arnd Bergmann <arnd@arndb.de> > --- > Originally submitted on July 14, but no reply. This is the same > patch again. The warning is currently disabled in mainline, but > I think we can turn it back on in the future, and this change here > seems harmless. > --- > drivers/gpu/drm/nouveau/nvkm/subdev/clk/gt215.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/clk/gt215.c b/drivers/gpu/drm/nouveau/nvkm/subdev/clk/gt215.c > index 96e0941c8edd..04b4f4ccf186 100644 > --- a/drivers/gpu/drm/nouveau/nvkm/subdev/clk/gt215.c > +++ b/drivers/gpu/drm/nouveau/nvkm/subdev/clk/gt215.c > @@ -130,10 +130,10 @@ read_pll(struct gt215_clk *clk, int idx, u32 pll) > sclk = read_clk(clk, 0x10 + idx, false); > } > > - if (M * P) > - return sclk * N / (M * P); > + if (M * P == 0) > + return 0; > > - return 0; > + return sclk * N / (M * P); > } > > static int > -- > 2.9.0 > > _______________________________________________ > Nouveau mailing list > Nouveau@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/nouveau
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