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

Jonathan Cameron
2022-09-22T10:59:41Z

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

> 302
> 303 mcp3911_scale_table[i][0] = 0;
> 304 mcp3911_scale_table[i][1] = tmp1;
> 305 }
> 306
> 307 return 0;
> 308 }
> 309
>