regulator: pf1550: fix division by zero in the ramp rate selection

set_machine_constraints() calls the set_ramp_delay() op when either
constraints->ramp_delay or constraints->ramp_disable is set. The
regulator binding documents regulator-ramp-delay = <0> as the way to
disable ramp control, and of_get_regulation_constraints() turns that
into ramp_disable = true while leaving ramp_delay at 0, so the op is
called with a ramp_delay of 0. The range check rejects negative values
and values above 6250 but not zero, and the value is then used as a
divisor.

The mapping is also wrong for the values that do pass the check. The
hardware offers two rates, 6250 uV/us and 3125 uV/us, selected by
SWx_DVSSPEED in SWx_CTRL1. Dividing 6250 by the requested rate and
taking bit 1 of the quotient does not map monotonically onto them: a
request for 1500 uV/us selects 6250 uV/us, while a request for the
faster 2000 uV/us selects 3125 uV/us.

Replace the division with a direct mapping onto the two supported
rates. Requests at or below 3125 uV/us get the slower rate and anything
above it gets the faster one. A ramp_delay of 0 asks for ramp control
to be disabled, which this hardware cannot do, so it gets the fastest
rate; pfuze100 handles the disabled case the same way.

Fixes: 7320d41c29bb ("regulator: pf1550: Add support for regulator")
Signed-off-by: Donggeun Yoo <donggeunyoo.kernel@gmail.com>
Link: https://patch.msgid.link/20260903082010.4024603-1-donggeunyoo.kernel@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>

0 files changed, 0 insertions, 0 deletions