Re: [PATCH v4 2/2] regulator: rpi-panel-v2: Add vcc-supply support

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] regulator: rpi-panel-v2: leaked enable count in rpi_panel_v2_i2c_probe()
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commit e10aa8754cb62ec300b893710f2607ab6d8e3548
Author: Shashank Maurya <shashank.maurya@oss.qualcomm.com>

regulator: rpi-panel-v2: Add vcc-supply support

This commit adds support for acquiring and enabling the vcc power supply in
rpi_panel_v2_i2c_probe() before accessing the panel MCU over I2C.

> diff --git a/drivers/regulator/rpi-panel-v2-regulator.c b/drivers/regulator/rpi-panel-v2-regulator.c
> index 30b78aa75ee38..e54d675962e71 100644
> --- a/drivers/regulator/rpi-panel-v2-regulator.c
> +++ b/drivers/regulator/rpi-panel-v2-regulator.c

[ ... ]

> @@ -66,10 +67,21 @@ static int rpi_panel_v2_i2c_probe(struct i2c_client *i2c)
>  		.parent		= &i2c->dev,
>  		.reg_set_base	= REG_POWERON,
>  	};
> +	struct regulator *vcc;
>  	struct regmap *regmap;
>  	struct pwm_chip *pc;
>  	int ret;
>  
> +	vcc = devm_regulator_get(&i2c->dev, "vcc");
> +	if (IS_ERR(vcc))
> +		return dev_err_probe(&i2c->dev, PTR_ERR(vcc),
> +				     "Failed to get vcc supply\n");
> +
> +	ret = regulator_enable(vcc);
> +	if (ret)
> +		return dev_err_probe(&i2c->dev, ret,
> +				     "Failed to enable vcc supply\n");

[Severity: High]
As reported by Sashiko on v2 [1], does this leak the vcc regulator enable
count when a subsequent call in rpi_panel_v2_i2c_probe() fails (such as
devm_pwmchip_alloc(), devm_regmap_init_i2c(), devm_gpio_regmap_register(), or
devm_pwmchip_add()), or when the driver is unbound?

Because vcc is acquired with devm_regulator_get() and enabled with an
unmanaged regulator_enable(), devres cleanup calls:

  devm_regulator_release()
    -> regulator_put()
      -> _regulator_put()

while regulator->enable_count is still 1, triggering
WARN_ON(regulator->enable_count) in _regulator_put() and leaving the
underlying regulator_dev use_count permanently elevated.

Should rpi_panel_v2_i2c_probe() use devm_regulator_get_enable(&i2c->dev,
"vcc") instead so that a devm action is registered to disable the supply
before releasing it?

[1] https://lore.kernel.org/r/20260907055129.010E71F00A3A@smtp.kernel.org

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Sashiko AI review · https://sashiko.dev/#/patchset/20261104-rpi_reg-v4-0-3578e794ff45@oss.qualcomm.com?part=2