Re: [PATCH v2] phy: qcom-qusb2: Add regulator_set_load to Qualcomm usb phy

[Song Xue <quic_songxue@quicinc.com>]

On 11/22/2024 6:24 AM, Dmitry Baryshkov wrote:
> On Thu, Nov 21, 2024 at 04:09:27PM +0800, Song Xue wrote:
>> Set the current load before enable regulator supplies at QUSB phy.
>>
>> Encountered one issue where the board powered down instantly once the UVC
>> camera was attached to USB port while adding host mode on usb port and
>> testing a UVC camera with the driver on QCS615 platform. The extensible
>> boot loader mentioned that OCP(Over Current Protection) occurred at LDO12
>> from regulators-0 upon powered on board again. That indicates that the
>> current load set for QUSB phy, which use the regulator supply, is lower
>> than expected.
>>
>> As per QUSB spec, set the maximum current load at 30mA to avoid overcurrent
>> load when attach a device to the USB port.
>>
>> Fixes: 937e17f36a32 ("phy: qcom-qusb2: Power-on PHY before initialization")
>> Signed-off-by: Song Xue <quic_songxue@quicinc.com>
>> ---
>> Changes in v2:
>> - Removed "---" above the Fixes.
>> - Link to v1: https://lore.kernel.org/r/20241121-add_set_load_to_qusb_phy-v1-1-0f44f3a3290e@quicinc.com
>> ---
>>   drivers/phy/qualcomm/phy-qcom-qusb2.c | 13 ++++++++++++-
>>   1 file changed, 12 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/phy/qualcomm/phy-qcom-qusb2.c b/drivers/phy/qualcomm/phy-qcom-qusb2.c
>> index c52655a383cef008552ed4533b9f31d1cbf34a13..80f0d17c42717e843937255a9a780bbae5998535 100644
>> --- a/drivers/phy/qualcomm/phy-qcom-qusb2.c
>> +++ b/drivers/phy/qualcomm/phy-qcom-qusb2.c
>> @@ -722,16 +722,27 @@ static int __maybe_unused qusb2_phy_runtime_resume(struct device *dev)
>>   	return ret;
>>   }
>>   
>> +#define QUSB2PHY_HPM_LOAD 30000 /*uA*/
>> +
>>   static int qusb2_phy_init(struct phy *phy)
>>   {
>>   	struct qusb2_phy *qphy = phy_get_drvdata(phy);
>>   	const struct qusb2_phy_cfg *cfg = qphy->cfg;
>>   	unsigned int val = 0;
>>   	unsigned int clk_scheme;
>> -	int ret;
>> +	int ret, i;
>>   
>>   	dev_vdbg(&phy->dev, "%s(): Initializing QUSB2 phy\n", __func__);
>>   
>> +	/* set the current load */
>> +	for (i = 0; i < ARRAY_SIZE(qphy->vregs); i++) {
>> +		ret = regulator_set_load(qphy->vregs[i].consumer, QUSB2PHY_HPM_LOAD);
> 
> Please use regulator_set_mode() instead. Or just fix the mode in the
> device tree, if the device can not operate if the regulator is in
> non-HPM mode.
> 
Thanks for comment.

 From my point, regulator_set_mode() will change the regulator's 
operating mode including current and voltage, which will also influence 
the other shared consumers. Meanwhile it is unacceptable to fix mode in 
the device tree because it is determined by regulator's device tree.

According to the required fix, regulator_set_load() simply aggregates 
the current load for the regulator and does not affect other shared 
consumers. Setting the current load is relevant to the issue.

Regards,
Song
>> +		if (ret) {
>> +			dev_err(&phy->dev, "failed to set load at %s\n", qphy->vregs[i].supply);
>> +			return ret;
>> +		}
>> +	}
>> +
>>   	/* turn on regulator supplies */
>>   	ret = regulator_bulk_enable(ARRAY_SIZE(qphy->vregs), qphy->vregs);
>>   	if (ret)
>>
>> ---
>> base-commit: decc701f41d07481893fdea942c0ac6b226e84cd
>> change-id: 20241121-add_set_load_to_qusb_phy-d1327c797ffe
>>
>> Best regards,
>> -- 
>> Song Xue <quic_songxue@quicinc.com>
>>
>