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

Hi Baruch, On Tue, Feb 08, 2022 at 08:51:40AM +0200, Baruch Siach wrote: As far as I am aware, casting to unsigned long long would be an appropriate way to fix this warning, as has been done in the following patches in mainline: c9ae8eed4463 ("media: omap3isp: avoid warnings at IS_OUT_OF_BOUNDS()") 4853396f03c3 ("memstick: avoid out-of-range warning") 7ff4034e910f ("staging: vc04_services: shut up out-of-range warning") a2fa9e57a68c ("ARM: mvebu: avoid clang -Wtautological-constant warning") The below diff fixes the warning for me with ARCH=hexagon allyesconfig: diff --git a/drivers/pwm/pwm-ipq.c b/drivers/pwm/pwm-ipq.c index 994027290bcb..7ea29468e76e 100644 --- a/drivers/pwm/pwm-ipq.c +++ b/drivers/pwm/pwm-ipq.c @@ -119,7 +119,7 @@ static int ipq_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, * period_ns is 1G or less. As long as rate is less than 16 GHz, * period_rate does not overflow. Make that explicit. */ - if (rate > 16ULL * GIGA) + if ((unsigned long long)rate > 16ULL * GIGA) return -EINVAL; period_rate = period_ns * rate; best_pre_div = IPQ_PWM_MAX_DIV; Alternatively, you could widen rate to unsigned long long / u64 but I don't know what kind of implications that has in this function but it has been done in other places: 95c58291ee70 ("drm/msm/submit: fix overflow check on 64-bit architectures") cfd6fb45cfaf ("crypto: ccree - avoid out-of-range warnings from clang") 335aea75b0d9 ("drm/amdgpu: fix warning for overflow check") 844b85dda2f5 ("ARM: keystone: fix integer overflow warning") While the warning is currently under W=1, I think it is one that we would like to turn on at some point so fixing instances as they come up helps us get closer to that goal. Cheers, Nathan > > 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 > > > -- > ~. .~ Tk Open Systems > =}------------------------------------------------ooO--U--Ooo------------{= > - baruch(a)tkos.co.il - tel: +972.52.368.4656, http://www.tkos.co.il - >