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    Subject[PATCH AUTOSEL 5.5 407/542] regulator: vctrl-regulator: Avoid deadlock getting and setting the voltage
    Date
    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
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