6.9-stable review patch. If anyone has any objections, please let me know.
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From: George Stark gnstark@salutedevices.com
[ Upstream commit 32c44e1fa921aebf8a5ef9f778534a30aab39313 ]
While calculating frequency for the given period u64 numbers are multiplied before division what can lead to overflow in theory so use secure mul_u64_u64_div_u64() which handles overflow correctly.
Fixes: 329db102a26d ("pwm: meson: make full use of common clock framework") Suggested-by: Uwe Kleine-König u.kleine-koenig@pengutronix.de Signed-off-by: George Stark gnstark@salutedevices.com Link: https://lore.kernel.org/r/20240425171253.2752877-4-gnstark@salutedevices.com Signed-off-by: Uwe Kleine-König u.kleine-koenig@pengutronix.de Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/pwm/pwm-meson.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/pwm/pwm-meson.c b/drivers/pwm/pwm-meson.c index b5d5fe4669993..e12b6ff70baba 100644 --- a/drivers/pwm/pwm-meson.c +++ b/drivers/pwm/pwm-meson.c @@ -175,7 +175,7 @@ static int meson_pwm_calc(struct pwm_chip *chip, struct pwm_device *pwm,
dev_dbg(pwmchip_parent(chip), "fin_freq: %ld Hz\n", fin_freq);
- cnt = div_u64(fin_freq * period, NSEC_PER_SEC); + cnt = mul_u64_u64_div_u64(fin_freq, period, NSEC_PER_SEC); if (cnt > 0xffff) { dev_err(pwmchip_parent(chip), "unable to get period cnt\n"); return -EINVAL; @@ -190,7 +190,7 @@ static int meson_pwm_calc(struct pwm_chip *chip, struct pwm_device *pwm, channel->hi = 0; channel->lo = cnt; } else { - duty_cnt = div_u64(fin_freq * duty, NSEC_PER_SEC); + duty_cnt = mul_u64_u64_div_u64(fin_freq, duty, NSEC_PER_SEC);
dev_dbg(pwmchip_parent(chip), "duty=%llu duty_cnt=%u\n", duty, duty_cnt);