Re: [PATCH 2/3] regulator: qcom_usb_vbus: Add support for PMI8998 VBUS

[Caleb Connolly <caleb.connolly@xxxxxxxxxx>]

Hi James,

On 2/12/25 01:07, James A. MacInnes wrote:
> This patch extends the Qualcomm USB VBUS regulator driver to support
> PMI8998 PMIC alongside the existing support for PM8150B.

Thanks for the patch!
> Key changes:
> - Added current limit tables specific to PMI8998.

I also played around with vbus on PMI8998 before for type-c support 
(unfortunately didn't make it's way to the lists yet...) and I needed 
some additional changes for this to work correctly. I found that it was 
possible for the overcurrent protection to be hit if the type-c port 
manager allowed the peripheral to pull current too early, and it's 
necessary to allow 2.5ms enable time.

PM8150b doesn't have these limitations (and supports the instant power 
role switch feature that's part of the type-c PD spec, allowing the 
power role to be switched without either side losing power e.g. when you 
unplug the power supply from a dock), hence it's only necessary for PMI8998.

I would suggest implementing a proper .is_enabled op to poll the status 
register for OTG_STATE_ENABLED and configuring 
qcom_usb_vbus_rdesc.enable_time = 250000;

Kind regards,

> - Dynamically configure the VBUS regulator based on the PMIC type.
> - Updated debug messages to reflect successful initialization for
>    supported PMICs.
> - Changed registration log message
>
> These changes ensure proper VBUS current limit configuration and
> compatibility across multiple Qualcomm PMICs.
>
> Signed-off-by: James A. MacInnes <james.a.macinnes@xxxxxxxxx>
> ---
>   drivers/regulator/qcom_usb_vbus-regulator.c | 38 ++++++++++++++++++---
>   1 file changed, 33 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/regulator/qcom_usb_vbus-regulator.c b/drivers/regulator/qcom_usb_vbus-regulator.c
> index cd94ed67621f..804dd1a9e057 100644
> --- a/drivers/regulator/qcom_usb_vbus-regulator.c
> +++ b/drivers/regulator/qcom_usb_vbus-regulator.c
> @@ -20,10 +20,30 @@
>   #define OTG_CFG				0x53
>   #define OTG_EN_SRC_CFG			BIT(1)
>   
> -static const unsigned int curr_table[] = {
> +struct msm_vbus_desc {
> +	const unsigned int *curr_table;
> +	unsigned int n_current_limits;
> +};
> +
> +static const unsigned int curr_table_pm8150b[] = {
>   	500000, 1000000, 1500000, 2000000, 2500000, 3000000,
>   };
>   
> +static const unsigned int curr_table_pmi8998[] = {
> +	250000, 500000, 750000, 1000000,
> +	1250000, 1500000, 1750000, 2000000,
> +};
> +
> +static const struct msm_vbus_desc msm_vbus_desc_pm8150b = {
> +	.curr_table = curr_table_pm8150b,
> +	.n_current_limits = ARRAY_SIZE(curr_table_pm8150b),
> +};
> +
> +static const struct msm_vbus_desc msm_vbus_desc_pmi8998 = {
> +	.curr_table = curr_table_pmi8998,
> +	.n_current_limits = ARRAY_SIZE(curr_table_pmi8998),
> +};
> +
>   static const struct regulator_ops qcom_usb_vbus_reg_ops = {
>   	.enable = regulator_enable_regmap,
>   	.disable = regulator_disable_regmap,
> @@ -37,8 +57,6 @@ static struct regulator_desc qcom_usb_vbus_rdesc = {
>   	.ops = &qcom_usb_vbus_reg_ops,
>   	.owner = THIS_MODULE,
>   	.type = REGULATOR_VOLTAGE,
> -	.curr_table = curr_table,
> -	.n_current_limits = ARRAY_SIZE(curr_table),
>   };
>   
>   static int qcom_usb_vbus_regulator_probe(struct platform_device *pdev)
> @@ -48,6 +66,7 @@ static int qcom_usb_vbus_regulator_probe(struct platform_device *pdev)
>   	struct regmap *regmap;
>   	struct regulator_config config = { };
>   	struct regulator_init_data *init_data;
> +	const struct msm_vbus_desc *quirks;
>   	int ret;
>   	u32 base;
>   
> @@ -68,6 +87,12 @@ static int qcom_usb_vbus_regulator_probe(struct platform_device *pdev)
>   	if (!init_data)
>   		return -ENOMEM;
>   
> +	quirks = of_device_get_match_data(dev);
> +	if (!quirks)
> +		return -ENODEV;
> +
> +	qcom_usb_vbus_rdesc.curr_table = quirks->curr_table;
> +	qcom_usb_vbus_rdesc.n_current_limits = quirks->n_current_limits;
>   	qcom_usb_vbus_rdesc.enable_reg = base + CMD_OTG;
>   	qcom_usb_vbus_rdesc.enable_mask = OTG_EN;
>   	qcom_usb_vbus_rdesc.csel_reg = base + OTG_CURRENT_LIMIT_CFG;
> @@ -80,18 +105,21 @@ static int qcom_usb_vbus_regulator_probe(struct platform_device *pdev)
>   	rdev = devm_regulator_register(dev, &qcom_usb_vbus_rdesc, &config);
>   	if (IS_ERR(rdev)) {
>   		ret = PTR_ERR(rdev);
> -		dev_err(dev, "not able to register vbus reg %d\n", ret);
> +		dev_err(dev, "Failed to register vbus reg %d\n", ret);
>   		return ret;
>   	}
>   
>   	/* Disable HW logic for VBUS enable */
>   	regmap_update_bits(regmap, base + OTG_CFG, OTG_EN_SRC_CFG, 0);
>   
> +	dev_dbg(dev, "Registered QCOM VBUS regulator\n");
> +
>   	return 0;
>   }
>   
>   static const struct of_device_id qcom_usb_vbus_regulator_match[] = {
> -	{ .compatible = "qcom,pm8150b-vbus-reg" },
> +	{ .compatible = "qcom,pm8150b-vbus-reg", .data = &msm_vbus_desc_pm8150b },
> +	{ .compatible = "qcom,pmi8998-vbus-reg", .data = &msm_vbus_desc_pmi8998 },
>   	{ }
>   };
>   MODULE_DEVICE_TABLE(of, qcom_usb_vbus_regulator_match);

--
Caleb (they/them)