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

[Song Xue <quic_songxue@quicinc.com>]

On 11/29/2024 12:43 AM, Bjorn Andersson 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>
> 
> The patch looks good. But if we describe the regulator(s) with
> regulator-allow-set-load; and not all the consumers vote for load, the
> sum of the load when USB phy is disabled goes to 0 and we will enter
> LPM.
> 
Hi, Bjorn

Thanks for comment.

We dived into the code and found the other all Qualcomm platform's 
device tree using the phy-qcom-qusb2's compatible don't use the 
"regulator-initial-mode = <RPMH_REGULATOR_MODE_HPM>" and 
"regulator-allow-set-load" together at the same time. We think the patch 
is safe now.

Therefore, can we merge the patch?

Thanks,
Song
> For this reason we're not doing any load requests today. Can you confirm
> that this works fine with a dtb where only HPM is permitted (as well as
> LPM and HPM)? If so I'd be in favor of us merging this change, but
> keeping the dts HPM-only until someone confirms that all consumers of
> these regulators specify load-votes.
> 
> Regards,
> Bjorn
> 
>> ---
>> 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);
>> +		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>
>>
>>