[bug report] drivers:iio:dac: Add AD3552R driver support

[Dan Carpenter <dan.carpenter@oracle.com>]

Hello Mihail Chindris,

The patch 8f2b54824b28: "drivers:iio:dac: Add AD3552R driver support"
from Dec 13, 2021, leads to the following Smatch static checker
warning:

    drivers/iio/dac/ad3552r.c:688 ad3552r_reset()
    warn: impossible condition '(val < 0) => (0-u16max < 0)'

    drivers/iio/dac/ad3552r.c:699 ad3552r_reset()
    warn: impossible condition '(val < 0) => (0-u16max < 0)'

drivers/iio/dac/ad3552r.c
    655 static int ad3552r_reset(struct ad3552r_desc *dac)
    656 {
    657         struct reg_addr_pool addr;
    658         int ret;
    659         u16 val;
                ^^^^^^^

    660 
    661         dac->gpio_reset = devm_gpiod_get_optional(&dac->spi->dev, "reset",
    662                                                   GPIOD_OUT_LOW);
    663         if (IS_ERR(dac->gpio_reset))
    664                 return dev_err_probe(&dac->spi->dev, PTR_ERR(dac->gpio_reset),
    665                                      "Error while getting gpio reset");
    666 
    667         if (dac->gpio_reset) {
    668                 /* Perform hardware reset */
    669                 usleep_range(10, 20);
    670                 gpiod_set_value_cansleep(dac->gpio_reset, 1);
    671         } else {
    672                 /* Perform software reset if no GPIO provided */
    673                 ret = ad3552r_update_reg_field(dac,
    674                                                AD3552R_REG_ADDR_INTERFACE_CONFIG_A,
    675                                                AD3552R_MASK_SOFTWARE_RESET,
    676                                                AD3552R_MASK_SOFTWARE_RESET);
    677                 if (ret < 0)
    678                         return ret;
    679 
    680         }
    681 
    682         addr.dac = dac;
    683         addr.addr = AD3552R_REG_ADDR_INTERFACE_CONFIG_B;
    684         ret = readx_poll_timeout(ad3552r_read_reg_wrapper, &addr, val,
    685                                  val == AD3552R_DEFAULT_CONFIG_B_VALUE ||
    686                                  val < 0,
                                         ^^^^^^^
Unsigned can't be < 0.

    687                                  5000, 50000);
--> 688         if (val < 0)
                    ^^^^^^^

    689                 ret = val;
    690         if (ret) {
    691                 dev_err(&dac->spi->dev, "Error while resetting");
    692                 return ret;
    693         }
    694 
    695         ret = readx_poll_timeout(ad3552r_read_reg_wrapper, &addr, val,
    696                                  !(val & AD3552R_MASK_INTERFACE_NOT_READY) ||
    697                                  val < 0,
                                         ^^^^^^^

    698                                  5000, 50000);
    699         if (val < 0)
                    ^^^^^^^

    700                 ret = val;
    701         if (ret) {
    702                 dev_err(&dac->spi->dev, "Error while resetting");
    703                 return ret;
    704         }
    705 
    706         return ad3552r_update_reg_field(dac,
    707                                         addr_mask_map[AD3552R_ADDR_ASCENSION][0],
    708                                         addr_mask_map[AD3552R_ADDR_ASCENSION][1],
    709                                         val);
    710 }

regards,
dan carpenter