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iio: gts-helper: Fix division loop

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[ 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.dnainternet.fi
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Matti Vaittinen 2024-02-12 13:20:09 +02:00 committed by Sasha Levin
parent 3328ff75f6
commit 9066bec62f
1 changed files with 1 additions and 14 deletions
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15
drivers/iio/industrialio-gts-helper.c
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@ -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);
}
/**