From: Matti Vaittinen mazziesaccount@gmail.com
[ Upstream commit bb76cc45dcdfcd962a5994b8fe19ab74fc6c3c3a ]
The loop based 64bit division may run for a long time when dividend is a lot bigger than the divider. Replace the division loop by the div64_u64() which implementation may be significantly faster.
Tested-by: Subhajit Ghosh subhajit.ghosh@tweaklogic.com Signed-off-by: Matti Vaittinen mazziesaccount@gmail.com Fixes: 38416c28e168 ("iio: light: Add gain-time-scale helpers") Link: https://lore.kernel.org/r/Zcn-6e-0-nh2WcfU@drtxq0yyyyyyyyyyyyyby-3.rev.dnain... Signed-off-by: Jonathan Cameron Jonathan.Cameron@huawei.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/iio/industrialio-gts-helper.c | 15 +-------------- 1 file changed, 1 insertion(+), 14 deletions(-)
diff --git a/drivers/iio/industrialio-gts-helper.c b/drivers/iio/industrialio-gts-helper.c index 7653261d2dc2b..b51eb6cb766f3 100644 --- a/drivers/iio/industrialio-gts-helper.c +++ b/drivers/iio/industrialio-gts-helper.c @@ -34,24 +34,11 @@ static int iio_gts_get_gain(const u64 max, const u64 scale) { u64 full = max; - int tmp = 1;
if (scale > full || !scale) return -EINVAL;
- if (U64_MAX - full < scale) { - /* Risk of overflow */ - if (full - scale < scale) - return 1; - - full -= scale; - tmp++; - } - - while (full > scale * (u64)tmp) - tmp++; - - return tmp; + return div64_u64(full, scale); }
/**