Commit 61d7fdc4 authored by Jeffrey Hugo's avatar Jeffrey Hugo Committed by Mark Brown

regulator: qcom_spmi: Fix math of spmi_regulator_set_voltage_time_sel

spmi_regulator_set_voltage_time_sel() calculates the amount of delay
needed as the result of setting a new voltage.  Essentially this is the
absolute difference of the old and new voltages, divided by the slew rate.

The implementation of spmi_regulator_set_voltage_time_sel() is wrong.

It attempts to calculate the difference in voltages by using the
difference in selectors and multiplying by the voltage step between
selectors.  This ignores the possibility that the old and new selectors
might be from different ranges, which have different step values.  Also,
the difference between the selectors may encapsulate N ranges inbetween,
so a summation of each selector change from old to new would be needed.

Lets avoid all of that complexity, and just get the actual voltage
represented by both the old and new selector, and use those to directly
compute the voltage delta.  This is more straight forward, and has the
side benifit of avoiding issues with regulator implementations that don't
have hardware register support to get the current configured range.

Fixes: e92a4047 ("regulator: Add QCOM SPMI regulator driver")
Reported-by: default avatarBjorn Andersson <bjorn.andersson@linaro.org>
Reported-by: default avatarJorge Ramirez-Ortiz <jorge.ramirez-ortiz@linaro.org>
Reported-by: default avatarMark Brown <broonie@kernel.org>
Signed-off-by: default avatarJeffrey Hugo <jeffrey.l.hugo@gmail.com>
Reviewed-by: default avatarBjorn Andersson <bjorn.andersson@linaro.org>
Tested-by: default avatarJorge Ramirez-Ortiz <jorge.ramirez-ortiz@linaro.org>
Signed-off-by: default avatarMark Brown <broonie@kernel.org>
parent fd5d1005
...@@ -813,14 +813,10 @@ static int spmi_regulator_set_voltage_time_sel(struct regulator_dev *rdev, ...@@ -813,14 +813,10 @@ static int spmi_regulator_set_voltage_time_sel(struct regulator_dev *rdev,
unsigned int old_selector, unsigned int new_selector) unsigned int old_selector, unsigned int new_selector)
{ {
struct spmi_regulator *vreg = rdev_get_drvdata(rdev); struct spmi_regulator *vreg = rdev_get_drvdata(rdev);
const struct spmi_voltage_range *range;
int diff_uV; int diff_uV;
range = spmi_regulator_find_range(vreg); diff_uV = abs(spmi_regulator_common_list_voltage(rdev, new_selector) -
if (!range) spmi_regulator_common_list_voltage(rdev, old_selector));
return -EINVAL;
diff_uV = abs(new_selector - old_selector) * range->step_uV;
return DIV_ROUND_UP(diff_uV, vreg->slew_rate); return DIV_ROUND_UP(diff_uV, vreg->slew_rate);
} }
......
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