diff options
| author | Andy Shevchenko <andriy.shevchenko@linux.intel.com> | 2026-06-18 16:49:34 +0200 |
|---|---|---|
| committer | Andi Shyti <andi.shyti@kernel.org> | 2026-06-23 17:28:25 +0200 |
| commit | 2e9a7f68329be41792c0b123c28e6c53c2fa2249 (patch) | |
| tree | 353fc430e7a3c5946967fe13b5f8b47f5c32800c /drivers/i2c | |
| parent | 1dc18801be29bc54709aa355b8acd80e183b03cd (diff) | |
i2c: mpc: Fix timeout calculations
At first glance the harmless cleanup of the driver does nothing bad.
However, as the operator precedence list states the '*' (multiplication)
and '/' division operators have order 5 with left-to-right associativity
the *= has order 17 and associativity right-to-left. It wouldn't be
a problem to replace
foo = foo * HZ / 1000000;
with
foo *= HZ / 1000000;
if HZ constant is in Hertz. The problem is that in the Linux kernel HZ is
defined in jiffy units, which is order of magnitude smaller than a million.
That's why operator precedence has a crucial role here. Fix the regression
by reverting pre-optimized calculations.
Fixes: be40a3ae719f ("i2c: mpc: Use of_property_read_u32 instead of of_get_property")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: <stable@vger.kernel.org> # v6.4+
Reviewed-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>
Link: https://lore.kernel.org/r/20260618144934.3249950-1-andriy.shevchenko@linux.intel.com
Diffstat (limited to 'drivers/i2c')
| -rw-r--r-- | drivers/i2c/busses/i2c-mpc.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/i2c/busses/i2c-mpc.c b/drivers/i2c/busses/i2c-mpc.c index 28c5c5c1fb7a..a21fa45bd64c 100644 --- a/drivers/i2c/busses/i2c-mpc.c +++ b/drivers/i2c/busses/i2c-mpc.c @@ -844,7 +844,7 @@ static int fsl_i2c_probe(struct platform_device *op) "fsl,timeout", &mpc_ops.timeout); if (!result) { - mpc_ops.timeout *= HZ / 1000000; + mpc_ops.timeout = mpc_ops.timeout * HZ / 1000000; if (mpc_ops.timeout < 5) mpc_ops.timeout = 5; } else { |