>From pwm_samsung_calc_tin(), there is routine to find the lowest divider possible to generate lower frequency than requested one. But it is always possible to generate requested frequency with large enough modulation bits, so this patch fixes to use lowest div for the case. This patch removes following UBSAN warning: UBSAN: Undefined behaviour in drivers/pwm/pwm-samsung.c:197:13 shift exponent 32 is too large for 32-bit type 'long unsigned int' [...] [<c0670248>] (ubsan_epilogue) from [<c06707b4>] (__ubsan_handle_shift_out_of_bounds+0xd8/0x120) [<c06707b4>] (__ubsan_handle_shift_out_of_bounds) from [<c0694b28>] (pwm_samsung_config+0x508/0x6a4) [<c0694b28>] (pwm_samsung_config) from [<c069286c>] (pwm_apply_state+0x174/0x40c) [<c069286c>] (pwm_apply_state) from [<c0b2e070>] (pwm_fan_probe+0xc8/0x488) [<c0b2e070>] (pwm_fan_probe) from [<c07ba8b0>] (platform_drv_probe+0x70/0x150) [...] Signed-off-by: Seung-Woo Kim <sw0312.kim@xxxxxxxxxxx> --- The UBSAN warning from ARM is reported with the patch in following link: https://patchwork.kernel.org/patch/9189575/ --- drivers/pwm/pwm-samsung.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/drivers/pwm/pwm-samsung.c b/drivers/pwm/pwm-samsung.c index ada2d32..ff0def6 100644 --- a/drivers/pwm/pwm-samsung.c +++ b/drivers/pwm/pwm-samsung.c @@ -193,9 +193,13 @@ static unsigned long pwm_samsung_calc_tin(struct samsung_pwm_chip *chip, * divider settings and choose the lowest divisor that can generate * frequencies lower than requested. */ - for (div = variant->div_base; div < 4; ++div) - if ((rate >> (variant->bits + div)) < freq) - break; + if (fls(rate) <= variant->bits) { + div = variant->div_base; + } else { + for (div = variant->div_base; div < 4; ++div) + if ((rate >> (variant->bits + div)) < freq) + break; + } pwm_samsung_set_divisor(chip, chan, BIT(div)); -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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