Re: [bug report] iio: dac: adding support for Microchip MCP47FEB02

[Andy Shevchenko <andriy.shevchenko@intel.com>]

On Fri, Feb 06, 2026 at 04:40:15PM +0300, Dan Carpenter wrote:
> [ Smatch checking is paused while we raise funding.  #SadFace
>   https://lore.kernel.org/all/aTaiGSbWZ9DJaGo7@stanley.mountain/ -dan ]
> 
> Hello Ariana Lazar,
> 
> Commit bf394cc80369 ("iio: dac: adding support for Microchip
> MCP47FEB02") from Dec 16, 2025 (linux-next), leads to the following
> Smatch static checker warning:
> 
> 	drivers/iio/dac/mcp47feb02.c:732 mcp47feb02_init_scales_avail()
> 	warn: passing zero to 'dev_err_probe'

Btw, why the bot mangles the patch, please?
Adding leading information (line number and some other markings) should not
mangle the code (tab-based indentation).

> drivers/iio/dac/mcp47feb02.c
>     712 static int mcp47feb02_init_scales_avail(struct mcp47feb02_data *data, int vdd_mV,
>     713                                         int vref_mV, int vref1_mV)
>     714 {
>     715         struct device *dev = regmap_get_device(data->regmap);
>     716         int tmp_vref;
>     717 
>     718         mcp47feb02_init_scale(data, MCP47FEB02_SCALE_VDD, vdd_mV, data->scale);
>     719 
>     720         if (data->use_vref)
>     721                 tmp_vref = vref_mV;
>     722         else
>     723                 tmp_vref = MCP47FEB02_INTERNAL_BAND_GAP_mV;
>     724 
>     725         mcp47feb02_init_scale(data, MCP47FEB02_SCALE_GAIN_X1, tmp_vref, data->scale);
>     726         mcp47feb02_init_scale(data, MCP47FEB02_SCALE_GAIN_X2, tmp_vref * 2, data->scale);
>     727 
>     728         if (data->phys_channels >= 4) {
>     729                 mcp47feb02_init_scale(data, MCP47FEB02_SCALE_VDD, vdd_mV, data->scale_1);
>     730 
>     731                 if (data->use_vref1 && vref1_mV <= 0)
> --> 732                         return dev_err_probe(dev, vref1_mV, "Invalid voltage for Vref1\n");
>                                                           ^^^^^^^^
> vref1_mV is not a valid error code.

Why not? When it's negative I believe the above statement is not true.

> Return -EINVAL.

Probably true for the == 0 case.

With the above, this probably should be

>     734                 if (data->use_vref1)
>     735                         tmp_vref = vref1_mV;
>     736                 else
>     737                         tmp_vref = MCP47FEB02_INTERNAL_BAND_GAP_mV;

                 if (data->use_vref1) {
                         if (vref1_mV < 0)
                                  return dev_err_probe(dev, vref1_mV, "Can't get voltage for Vref1\n");
			 if (vref1_mV == 0)
                                  return dev_err_probe(dev, -ERANGE, "Invalid voltage for Vref1\n");
			 // or -EINVAL?
                         tmp_vref = vref1_mV;
		 } else {
                         tmp_vref = MCP47FEB02_INTERNAL_BAND_GAP_mV;
		 }


>     739                 mcp47feb02_init_scale(data, MCP47FEB02_SCALE_GAIN_X1,
>     740                                       tmp_vref, data->scale_1);
>     741                 mcp47feb02_init_scale(data, MCP47FEB02_SCALE_GAIN_X2,
>     742                                       tmp_vref * 2, data->scale_1);
>     743         }
>     744 
>     745         return 0;
>     746 }

-- 
With Best Regards,
Andy Shevchenko