[PATCH 5.5 298/399] regulator: vctrl-regulator: Avoid deadlock getting and setting the voltage

Greg Kroah-Hartman
2020-02-21T07:56:35Z

From: Enric Balletbo i Serra <enric.balletbo@collabora.com>

[ Upstream commit e9153311491da9d9863ead9888a1613531cb4a1b ]

`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: f8702f9e4aa7 ("regulator: core: Use ww_mutex for regulators locking")
Reported-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Link: https://lore.kernel.org/r/20200116094543.2847321-1-enric.balletbo@collabora.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/regulator/core.c | 2 ++
drivers/regulator/vctrl-regulator.c | 38 +++++++++++++++++------------
2 files changed, 25 insertions(+), 15 deletions(-)

diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index 03d79fee2987e..e7d167ce326cb 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -3470,6 +3470,7 @@ 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)
@@ -4034,6 +4035,7 @@ 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
diff --git a/drivers/regulator/vctrl-regulator.c b/drivers/regulator/vctrl-regulator.c
index 9a9ee81881098..cbadb1c996790 100644
--- a/drivers/regulator/vctrl-regulator.c
+++ b/drivers/regulator/vctrl-regulator.c
@@ -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;
@@ -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);
}
@@ -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;
@@ -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;

@@ -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;
}
@@ -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;

@@ -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",
@@ -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,
@@ -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;
--
2.20.1