Unverified Commit e9153311 authored by Enric Balletbo i Serra's avatar Enric Balletbo i Serra Committed by Mark Brown
Browse files

regulator: vctrl-regulator: Avoid deadlock getting and setting the voltage 



`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: f8702f9e ("regulator: core: Use ww_mutex for regulators locking")
Reported-by: default avatarDouglas Anderson <dianders@chromium.org>
Signed-off-by: default avatarEnric Balletbo i Serra <enric.balletbo@collabora.com>
Link: https://lore.kernel.org/r/20200116094543.2847321-1-enric.balletbo@collabora.com


Signed-off-by: default avatarMark Brown <broonie@kernel.org>
parent 6f1ff761

drivers/regulator/core.c

+2 −0
Original line number Diff line number Diff line
@@ -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)
@@ -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

drivers/regulator/vctrl-regulator.c

+23 −15
Original line number Diff line number Diff line
@@ -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;

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