linux-kernel - Re: [PATCH v6 2/2] usb: typec: hd3ss3220: Enable VBUS based on ID pin state

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Message-ID: <9bd003e0-4600-4b5f-97d7-efefe687f358@oss.qualcomm.com>
Date: Thu, 6 Nov 2025 21:01:03 +0530
From: Krishna Kurapati PSSNV <krishna.kurapati@....qualcomm.com>
To: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Rob Herring <robh@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Biju Das <biju.das.jz@...renesas.com>,
        Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>,
        linux-usb@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v6 2/2] usb: typec: hd3ss3220: Enable VBUS based on ID pin
 state



On 11/6/2025 3:35 PM, Heikki Krogerus wrote:
> Hi Krishna,
> 
> Sun, Nov 02, 2025 at 10:18:19PM +0530, Krishna Kurapati kirjoitti:
>> There is a ID pin present on HD3SS3220 controller that can be routed
>> to SoC. As per the datasheet:
>>
>> "Upon detecting a UFP device, HD3SS3220 will keep ID pin high if VBUS is
>> not at VSafe0V. Once VBUS is at VSafe0V, the HD3SS3220 will assert ID pin
>> low. This is done to enforce Type-C requirement that VBUS must be at
>> VSafe0V before re-enabling VBUS"
>>
>> Add support to read the ID pin state and enable VBUS accordingly.
>>
>> Signed-off-by: Krishna Kurapati <krishna.kurapati@....qualcomm.com>
>> ---
>>   drivers/usb/typec/hd3ss3220.c | 72 +++++++++++++++++++++++++++++++++++
>>   1 file changed, 72 insertions(+)
>>
>> diff --git a/drivers/usb/typec/hd3ss3220.c b/drivers/usb/typec/hd3ss3220.c
>> index 3ecc688dda82..75fbda42eaf4 100644
>> --- a/drivers/usb/typec/hd3ss3220.c
>> +++ b/drivers/usb/typec/hd3ss3220.c
>> @@ -15,6 +15,9 @@
>>   #include <linux/usb/typec.h>
>>   #include <linux/delay.h>
>>   #include <linux/workqueue.h>
>> +#include <linux/gpio/consumer.h>
>> +#include <linux/regulator/consumer.h>
>> +#include <linux/of_graph.h>
>>   
>>   #define HD3SS3220_REG_CN_STAT		0x08
>>   #define HD3SS3220_REG_CN_STAT_CTRL	0x09
>> @@ -54,6 +57,11 @@ struct hd3ss3220 {
>>   	struct delayed_work output_poll_work;
>>   	enum usb_role role_state;
>>   	bool poll;
>> +
>> +	struct gpio_desc *id_gpiod;
>> +	int id_irq;
>> +
>> +	struct regulator *vbus;
>>   };
>>   
>>   static int hd3ss3220_set_power_opmode(struct hd3ss3220 *hd3ss3220, int power_opmode)
>> @@ -319,6 +327,44 @@ static const struct regmap_config config = {
>>   	.max_register = 0x0A,
>>   };
>>   
>> +static irqreturn_t hd3ss3220_id_isr(int irq, void *dev_id)
>> +{
>> +	struct hd3ss3220 *hd3ss3220 = dev_id;
>> +	int ret;
>> +	int id;
>> +
>> +	if (!hd3ss3220->vbus)
>> +		return IRQ_HANDLED;
> 
> If you don't need this routine unless there is a vbus regulator, then
> don't register it at all if there is no vbus regulator.
> 

Will move vbus check before id retrieval in probe and ignore retrieval 
of ID if vbus is absent.

>> +	id = hd3ss3220->id_gpiod ? gpiod_get_value_cansleep(hd3ss3220->id_gpiod) : 1;
> 
> You still don't need to check for hd3ss3220->id_gpiod - this function
> will not get called unless it's there.
> 
>          if (gpiod_get_value_cansleep(hd3ss3220->id_gpiod))
>                  ret = regulator_disable(hd3ss3220->vbus);
>          else
>                  ret = regulator_enable(hd3ss3220->vbus);
> 

ACK.

> Note:
> 
> If you are concerned that the reference to the id_gpiod may be
> released before this routine is unregistered, then that condition will
> not help. The hd3ss3220->id_gpiod member is _not_ NULL after the
> reference is released.
> 
> If you need a specific order in which the references are released,
> then you can't use the resource management (devm_*) to automate things
> for you.

There is no specific order. So the id part I can keep it intact except 
for checking presence of ID pin in interrupt handler.

> 
>> +	if (!id) {
>> +		ret = regulator_enable(hd3ss3220->vbus);
>> +		if (ret)
>> +			dev_err(hd3ss3220->dev, "enable vbus regulator failed\n");
>> +	} else {
>> +		regulator_disable(hd3ss3220->vbus);
>> +	}
>> +
>> +	return IRQ_HANDLED;
>> +}
>> +
>> +static int hd3ss3220_get_vbus_supply(struct hd3ss3220 *hd3ss3220,
>> +				     struct fwnode_handle *connector)
>> +{
>> +	int ret  = 0;
>> +
>> +	hd3ss3220->vbus = devm_of_regulator_get_optional(hd3ss3220->dev,
>> +							 to_of_node(connector),
>> +							 "vbus");
>> +	if (PTR_ERR(hd3ss3220->vbus) == -ENODEV)
>> +		hd3ss3220->vbus = NULL;
>> +	else if (IS_ERR(hd3ss3220->vbus))
>> +		ret = PTR_ERR(hd3ss3220->vbus);
> 
> So the regulator API's optional functions return -ENODEV instead of NULL :(
> In any case, don't double assign the member. Use local variable.
> 
>          struct regulator *vbus;
> 
>          vbus = devm_of_regulator_get_optional(...
>          if (IS_ERR(vbus) && vbus != ERR_PTR(-ENODEV))
>                  return PTR_ERR(vbus);
> 
>          hd3ss3220->vbus = vbus;
>          return 0;
> 
> I don't think you need this function - just do that in the probe function.
> 

ACK.

Regards,
Krishna,