Re: [jic23-iio:testing 58/58] drivers/iio/adc/mcp3911.c:274:6: warning: variable 'tmp0' set but not used

Jonathan Cameron
2022-09-22T16:29:21Z

On Thu, 22 Sep 2022 17:41:25 +0200
Marcus Folkesson <marcus.folkesson@gmail.com> wrote:

> On Thu, Sep 22, 2022 at 11:59:25AM +0100, Jonathan Cameron wrote:
> > On Thu, 22 Sep 2022 08:50:17 +0800
> > kernel test robot <lkp@intel.com> wrote:
> >
> > > tree: https://git.kernel.org/pub/scm/linux/kernel/git/jic23/iio.git testing
> > > head: d4e1a549566b9ea8b96e80f0cdcbe99714ac256e
> > > commit: d4e1a549566b9ea8b96e80f0cdcbe99714ac256e [58/58] iio: adc: mcp3911: add support to set PGA
> > > config: x86_64-randconfig-a012
> > > compiler: clang version 14.0.6 (https://github.com/llvm/llvm-project f28c006a5895fc0e329fe15fead81e37457cb1d1)
> > > reproduce (this is a W=1 build):
> > > wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
> > > chmod +x ~/bin/make.cross
> > > # https://git.kernel.org/pub/scm/linux/kernel/git/jic23/iio.git/commit/?id=d4e1a549566b9ea8b96e80f0cdcbe99714ac256e
> > > git remote add jic23-iio https://git.kernel.org/pub/scm/linux/kernel/git/jic23/iio.git
> > > git fetch --no-tags jic23-iio testing
> > > git checkout d4e1a549566b9ea8b96e80f0cdcbe99714ac256e
> > > # save the config file
> > > mkdir build_dir && cp config build_dir/.config
> > > COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash drivers/iio/adc/
> > >
> > > If you fix the issue, kindly add following tag where applicable
> > > | Reported-by: kernel test robot <lkp@intel.com>
> > >
> > > All warnings (new ones prefixed by >>):
> > >
> > > >> drivers/iio/adc/mcp3911.c:274:6: warning: variable 'tmp0' set but not used [-Wunused-but-set-variable]
> > > int tmp0, tmp1;
> > > ^
> > > 1 warning generated.
> > >
> > >
> > > vim +/tmp0 +274 drivers/iio/adc/mcp3911.c
> > >
> > > 268
> > > 269 static int mcp3911_calc_scale_table(struct mcp3911 *adc)
> > > 270 {
> > > 271 u32 ref = MCP3911_INT_VREF_MV;
> > > 272 u32 div;
> > > 273 int ret;
> > > > 274 int tmp0, tmp1;
> > > 275 s64 tmp2;
> > > 276
> > > 277 if (adc->vref) {
> > > 278 ret = regulator_get_voltage(adc->vref);
> > > 279 if (ret < 0) {
> > > 280 dev_err(&adc->spi->dev,
> > > 281 "failed to get vref voltage: %d\n",
> > > 282 ret);
> > > 283 return ret;
> > > 284 }
> > > 285
> > > 286 ref = ret / 1000;
> > > 287 }
> > > 288
> > > 289 /*
> > > 290 * For 24-bit Conversion
> > > 291 * Raw = ((Voltage)/(Vref) * 2^23 * Gain * 1.5
> > > 292 * Voltage = Raw * (Vref)/(2^23 * Gain * 1.5)
> > > 293 *
> > > 294 * ref = Reference voltage
> > > 295 * div = (2^23 * 1.5 * gain) = 12582912 * gain
> > > 296 */
> > > 297 for (int i = 0; i < MCP3911_NUM_SCALES; i++) {
> > > 298 div = 12582912 * BIT(i);
> > > 299 tmp2 = div_s64((s64)ref * 1000000000LL, div);
> > > 300 tmp1 = div;
> > > 301 tmp0 = (int)div_s64_rem(tmp2, 1000000000, &tmp1);
> >
> > Marcus,
> > I'm guessing the intent here is just to get the remainder.
> > Hence fix is probably just to drop tmp0?
> >
> > If you confirm that I'll tweak the commit to do that.
> >
> > Jonathan
>
>
> Hum, Yes. I actually think we can drop div, tmp0, tmp1 and tmp2.
> I think they are remnats for when I did the calculation differently.
>
> Do you want me to update the patchset?

No I'll roll this in a few minutes.

>
> static int mcp3911_calc_scale_table(struct mcp3911 *adc)
> {
> u32 ref = MCP3911_INT_VREF_MV;
> - u32 div;
> int ret;
> - int tmp0, tmp1;
> - s64 tmp2;
>
>
> ....
>
>
>
> for (int i = 0; i < MCP3911_NUM_SCALES; i++) {
> - div = 12582912 * BIT(i);
> - tmp2 = div_s64((s64)ref * 1000000000LL, div);
> - tmp1 = div;
> - tmp0 = (int)div_s64_rem(tmp2, 1000000000, &tmp1);
> -
> mcp3911_scale_table[i][0] = 0;
> - mcp3911_scale_table[i][1] = tmp1;
> + mcp3911_scale_table[i][1] = 12582912 * BIT(i);
> }
>
>
> /Marcus
>
> >
> >
> > > 302
> > > 303 mcp3911_scale_table[i][0] = 0;
> > > 304 mcp3911_scale_table[i][1] = tmp1;
> > > 305 }
> > > 306
> > > 307 return 0;
> > > 308 }
> > > 309
> > >
> >
>