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regulator: vctrl-regulator: Avoid deadlock getting and setting the vo…
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…ltage

`cat /sys/kernel/debug/regulator/regulator_summary` ends on a deadlock
when you have a voltage controlled regulator (vctrl).

The problem is that the vctrl_get_voltage() and vctrl_set_voltage() calls the
regulator_get_voltage() and regulator_set_voltage() and that will try to lock
again the dependent regulators (the regulator supplying the control voltage).

Fix the issue by exporting the unlocked version of the regulator_get_voltage()
and regulator_set_voltage() API so drivers that need it, like the voltage
controlled regulator driver can use it.

Fixes: f8702f9 ("regulator: core: Use ww_mutex for regulators locking")
Reported-by: Douglas Anderson <[email protected]>
Signed-off-by: Enric Balletbo i Serra <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Mark Brown <[email protected]>
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@broonie
Enric Balletbo i Serra authored and broonie committed Jan 17, 2020
1 parent 6f1ff76 commit e915331
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Showing 2 changed files with 25 additions and 15 deletions.
2 changes: 2 additions & 0 deletions drivers/regulator/core.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -3466,6 +3466,7 @@ int regulator_set_voltage_rdev(struct regulator_dev *rdev, int min_uV,
out:
return ret;
}
EXPORT_SYMBOL(regulator_set_voltage_rdev);

static int regulator_limit_voltage_step(struct regulator_dev *rdev,
int *current_uV, int *min_uV)
Expand Down Expand Up @@ -4030,6 +4031,7 @@ int regulator_get_voltage_rdev(struct regulator_dev *rdev)
return ret;
return ret - rdev->constraints->uV_offset;
}
EXPORT_SYMBOL(regulator_get_voltage_rdev);

/**
* regulator_get_voltage - get regulator output voltage
Expand Down
38 changes: 23 additions & 15 deletions drivers/regulator/vctrl-regulator.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -11,10 +11,13 @@
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/regulator/coupler.h>
#include <linux/regulator/driver.h>
#include <linux/regulator/of_regulator.h>
#include <linux/sort.h>

#include "internal.h"

struct vctrl_voltage_range {
int min_uV;
int max_uV;
Expand Down Expand Up @@ -79,7 +82,7 @@ static int vctrl_calc_output_voltage(struct vctrl_data *vctrl, int ctrl_uV)
static int vctrl_get_voltage(struct regulator_dev *rdev)
{
struct vctrl_data *vctrl = rdev_get_drvdata(rdev);
int ctrl_uV = regulator_get_voltage(vctrl->ctrl_reg);
int ctrl_uV = regulator_get_voltage_rdev(vctrl->ctrl_reg->rdev);

return vctrl_calc_output_voltage(vctrl, ctrl_uV);
}
Expand All @@ -90,16 +93,16 @@ static int vctrl_set_voltage(struct regulator_dev *rdev,
{
struct vctrl_data *vctrl = rdev_get_drvdata(rdev);
struct regulator *ctrl_reg = vctrl->ctrl_reg;
int orig_ctrl_uV = regulator_get_voltage(ctrl_reg);
int orig_ctrl_uV = regulator_get_voltage_rdev(ctrl_reg->rdev);
int uV = vctrl_calc_output_voltage(vctrl, orig_ctrl_uV);
int ret;

if (req_min_uV >= uV || !vctrl->ovp_threshold)
/* voltage rising or no OVP */
return regulator_set_voltage(
ctrl_reg,
return regulator_set_voltage_rdev(ctrl_reg->rdev,
vctrl_calc_ctrl_voltage(vctrl, req_min_uV),
vctrl_calc_ctrl_voltage(vctrl, req_max_uV));
vctrl_calc_ctrl_voltage(vctrl, req_max_uV),
PM_SUSPEND_ON);

while (uV > req_min_uV) {
int max_drop_uV = (uV * vctrl->ovp_threshold) / 100;
Expand All @@ -114,9 +117,10 @@ static int vctrl_set_voltage(struct regulator_dev *rdev,
next_uV = max_t(int, req_min_uV, uV - max_drop_uV);
next_ctrl_uV = vctrl_calc_ctrl_voltage(vctrl, next_uV);

ret = regulator_set_voltage(ctrl_reg,
ret = regulator_set_voltage_rdev(ctrl_reg->rdev,
next_ctrl_uV,
next_ctrl_uV,
next_ctrl_uV);
PM_SUSPEND_ON);
if (ret)
goto err;

Expand All @@ -130,7 +134,8 @@ static int vctrl_set_voltage(struct regulator_dev *rdev,

err:
/* Try to go back to original voltage */
regulator_set_voltage(ctrl_reg, orig_ctrl_uV, orig_ctrl_uV);
regulator_set_voltage_rdev(ctrl_reg->rdev, orig_ctrl_uV, orig_ctrl_uV,
PM_SUSPEND_ON);

return ret;
}
Expand All @@ -155,9 +160,10 @@ static int vctrl_set_voltage_sel(struct regulator_dev *rdev,

if (selector >= vctrl->sel || !vctrl->ovp_threshold) {
/* voltage rising or no OVP */
ret = regulator_set_voltage(ctrl_reg,
ret = regulator_set_voltage_rdev(ctrl_reg->rdev,
vctrl->vtable[selector].ctrl,
vctrl->vtable[selector].ctrl,
vctrl->vtable[selector].ctrl);
PM_SUSPEND_ON);
if (!ret)
vctrl->sel = selector;

Expand All @@ -173,9 +179,10 @@ static int vctrl_set_voltage_sel(struct regulator_dev *rdev,
else
next_sel = vctrl->vtable[vctrl->sel].ovp_min_sel;

ret = regulator_set_voltage(ctrl_reg,
ret = regulator_set_voltage_rdev(ctrl_reg->rdev,
vctrl->vtable[next_sel].ctrl,
vctrl->vtable[next_sel].ctrl);
vctrl->vtable[next_sel].ctrl,
PM_SUSPEND_ON);
if (ret) {
dev_err(&rdev->dev,
"failed to set control voltage to %duV\n",
Expand All @@ -195,9 +202,10 @@ static int vctrl_set_voltage_sel(struct regulator_dev *rdev,
err:
if (vctrl->sel != orig_sel) {
/* Try to go back to original voltage */
if (!regulator_set_voltage(ctrl_reg,
if (!regulator_set_voltage_rdev(ctrl_reg->rdev,
vctrl->vtable[orig_sel].ctrl,
vctrl->vtable[orig_sel].ctrl,
vctrl->vtable[orig_sel].ctrl))
PM_SUSPEND_ON))
vctrl->sel = orig_sel;
else
dev_warn(&rdev->dev,
Expand Down Expand Up @@ -482,7 +490,7 @@ static int vctrl_probe(struct platform_device *pdev)
if (ret)
return ret;

ctrl_uV = regulator_get_voltage(vctrl->ctrl_reg);
ctrl_uV = regulator_get_voltage_rdev(vctrl->ctrl_reg->rdev);
if (ctrl_uV < 0) {
dev_err(&pdev->dev, "failed to get control voltage\n");
return ctrl_uV;
Expand Down

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