linux-kernel - Re: drivers/hwmon/jc42.c:477 jc42_readable_reg() warn: always true condition '(reg >= 0) => (0-u32max >= 0)'

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Message-ID: <CAFBinCAB0VuoKKm4YHv_zB1d1xN3nP0=-xg9EotiWMJ_vikc2w@mail.gmail.com>
Date:   Thu, 22 Dec 2022 22:20:13 +0100
From:   Martin Blumenstingl <martin.blumenstingl@...glemail.com>
To:     Guenter Roeck <linux@...ck-us.net>
Cc:     kernel test robot <lkp@...el.com>, oe-kbuild-all@...ts.linux.dev,
        linux-kernel@...r.kernel.org, linux-hwmon@...r.kernel.org
Subject: Re: drivers/hwmon/jc42.c:477 jc42_readable_reg() warn: always true
 condition '(reg >= 0) => (0-u32max >= 0)'

Hi Guenter et al.,

On Thu, Dec 22, 2022 at 3:36 PM kernel test robot <lkp@...el.com> wrote:
[...]
>    475  static bool jc42_readable_reg(struct device *dev, unsigned int reg)
>    476  {
>  > 477          return (reg >= JC42_REG_CAP && reg <= JC42_REG_DEVICEID) ||
>    478                  reg == JC42_REG_SMBUS;
The bot is right: we can omit "reg >= JC42_REG_CAP" as it's already
covered by the fact that:
- the reg variable is unsigned, which means the lower limit is zero
- reg <= JC42_REG_DEVICEID covers the upper limit

Before I send a patch I'd like to hear if removal of "reg >=
JC42_REG_CAP" makes sense to other people.


Best regards,
Martin