Re: [PATCH 1/3] pwm: driver for qualcomm ipq6018 pwm block

[kernel test robot <lkp@intel.com>]

Hi Baruch,

I love your patch! Perhaps something to improve:

[auto build test WARNING on thierry-reding-pwm/for-next]
[also build test WARNING on robh/for-next v5.17-rc3 next-20220207]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Baruch-Siach/pwm-driver-for-qualcomm-ipq6018-pwm-block/20220207-175605
base:   https://git.kernel.org/pub/scm/linux/kernel/git/thierry.reding/linux-pwm.git for-next
config: hexagon-allyesconfig (https://download.01.org/0day-ci/archive/20220208/202202080410.R0qwqtXx-lkp@intel.com/config)
compiler: clang version 15.0.0 (https://github.com/llvm/llvm-project 0d8850ae2cae85d49bea6ae0799fa41c7202c05c)
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://github.com/0day-ci/linux/commit/71e449eb6d19b141b4527caae529e16c52bcfeea
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Baruch-Siach/pwm-driver-for-qualcomm-ipq6018-pwm-block/20220207-175605
        git checkout 71e449eb6d19b141b4527caae529e16c52bcfeea
        # save the config file to linux build tree
        mkdir build_dir
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=hexagon SHELL=/bin/bash drivers/pwm/

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

>> drivers/pwm/pwm-ipq.c:122:11: warning: result of comparison of constant 16000000000 with expression of type 'unsigned long' is always false [-Wtautological-constant-out-of-range-compare]
           if (rate > 16ULL * GIGA)
               ~~~~ ^ ~~~~~~~~~~~~
   1 warning generated.


vim +122 drivers/pwm/pwm-ipq.c

    99	
   100	static int ipq_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
   101				 const struct pwm_state *state)
   102	{
   103		struct ipq_pwm_chip *ipq_chip = ipq_pwm_from_chip(chip);
   104		unsigned int pre_div, pwm_div, best_pre_div, best_pwm_div;
   105		unsigned long rate = clk_get_rate(ipq_chip->clk);
   106		u64 period_ns, duty_ns, period_rate;
   107		u64 min_diff;
   108	
   109		if (state->polarity != PWM_POLARITY_NORMAL)
   110			return -EINVAL;
   111	
   112		if (state->period < DIV64_U64_ROUND_UP(NSEC_PER_SEC, rate))
   113			return -ERANGE;
   114	
   115		period_ns = min(state->period, IPQ_PWM_MAX_PERIOD_NS);
   116		duty_ns = min(state->duty_cycle, period_ns);
   117	
   118		/*
   119		 * period_ns is 1G or less. As long as rate is less than 16 GHz,
   120		 * period_rate does not overflow. Make that explicit.
   121		 */
 > 122		if (rate > 16ULL * GIGA)
   123			return -EINVAL;
   124		period_rate = period_ns * rate;
   125		best_pre_div = IPQ_PWM_MAX_DIV;
   126		best_pwm_div = IPQ_PWM_MAX_DIV;
   127		/*
   128		 * We don't need to consider pre_div values smaller than
   129		 *
   130		 *                              period_rate
   131		 *  pre_div_min := ------------------------------------
   132		 *                 NSEC_PER_SEC * (IPQ_PWM_MAX_DIV + 1)
   133		 *
   134		 * because pre_div = pre_div_min results in a better
   135		 * approximation.
   136		 */
   137		pre_div = div64_u64(period_rate,
   138				(u64)NSEC_PER_SEC * (IPQ_PWM_MAX_DIV + 1));
   139		min_diff = period_rate;
   140	
   141		for (; pre_div <= IPQ_PWM_MAX_DIV; pre_div++) {
   142			u64 remainder;
   143	
   144			pwm_div = div64_u64_rem(period_rate,
   145					(u64)NSEC_PER_SEC * (pre_div + 1), &remainder);
   146			/* pwm_div is unsigned; the check below catches underflow */
   147			pwm_div--;
   148	
   149			/*
   150			 * Swapping values for pre_div and pwm_div produces the same
   151			 * period length. So we can skip all settings with pre_div >
   152			 * pwm_div which results in bigger constraints for selecting
   153			 * the duty_cycle than with the two values swapped.
   154			 */
   155			if (pre_div > pwm_div)
   156				break;
   157	
   158			/*
   159			 * Make sure we can do 100% duty cycle where
   160			 * hi_dur == pwm_div + 1
   161			 */
   162			if (pwm_div > IPQ_PWM_MAX_DIV - 1)
   163				continue;
   164	
   165			if (remainder < min_diff) {
   166				best_pre_div = pre_div;
   167				best_pwm_div = pwm_div;
   168				min_diff = remainder;
   169	
   170				if (min_diff == 0) /* bingo */
   171					break;
   172			}
   173		}
   174	
   175		/* config divider values for the closest possible frequency */
   176		config_div_and_duty(pwm, best_pre_div, best_pwm_div,
   177				    rate, duty_ns, state->enabled);
   178	
   179		return 0;
   180	}
   181	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org