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

[Song Xue <quic_songxue@quicinc.com>]

On 12/13/2024 4:15 PM, Song Xue wrote:
> 
> 
> 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

Hi, Bjorn

As mentioned in the above comment, the code is safe for setting the 
load. Additionally, we can see that the patch for setting the current 
load for EMMC on QCS615 has been applied.

https://lore.kernel.org/all/20250114083514.258379-1-quic_yuanjiey@quicinc.com/

could you pls help confirm if apply 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>
>>>
>>>
> 
>