5:51 p.m.
Hi test robot,
Thanks for testing and reporting.
On Tue, Feb 08 2022, kernel test robot wrote:
[snip]
>> 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.
This clang warning is only enabled with W=1 (see commit
afe956c577b). Not sure how to avoid it.
Is there a way to express this condition without making clang warn on
platforms where ULONG_MAX == 2^32? Maybe cast to unsigned long long? Or
should we just ignore this W=1 warning?
baruch
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
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