linux-kernel - Re: [PATCH V3 2/2] phy: qcom-qmp-ufs: Add regulator loads for SM8650 and SM8750

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Message-ID: <61070746-431d-4adf-9e68-7ae9646a44c9@quicinc.com>
Date: Fri, 22 Aug 2025 17:09:14 +0530
From: Nitin Rawat <quic_nitirawa@...cinc.com>
To: Manivannan Sadhasivam <mani@...nel.org>
CC: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>, <vkoul@...nel.org>,
        <kishon@...nel.org>, <andersson@...nel.org>, <konradybcio@...nel.org>,
        <linux-arm-msm@...r.kernel.org>, <linux-phy@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH V3 2/2] phy: qcom-qmp-ufs: Add regulator loads for SM8650
 and SM8750



On 8/22/2025 4:26 PM, Manivannan Sadhasivam wrote:
> On Fri, Aug 22, 2025 at 02:53:31PM GMT, Nitin Rawat wrote:
>>
>>
>> On 8/22/2025 2:45 PM, Dmitry Baryshkov wrote:
>>> On 22/08/2025 11:53, Manivannan Sadhasivam wrote:
>>>> On Wed, Aug 20, 2025 at 03:49:31AM GMT, Dmitry Baryshkov wrote:
>>>>> On Wed, Aug 20, 2025 at 03:58:26AM +0530, Nitin Rawat wrote:
>>>>>> Add regulator load voting support for SM8650 and SM8750 platforms by
>>>>>> introducing dedicated regulator bulk data arrays with their load
>>>>>> values.
>>>>>>
>>>>>> The load requirements are:
>>>>>> - SM8650: vdda-phy (205mA), vdda-pll (17.5mA)
>>>>>> - SM8750: vdda-phy (213mA), vdda-pll (18.3mA)
>>>>>>
>>>>>> This ensures stable operation and proper power management for these
>>>>>> platforms where regulators are shared between the QMP USB PHY and
>>>>>> other IP blocks by setting appropriate regulator load
>>>>>> currents during PHY
>>>>>> operations.
>>>>>>
>>>>>> Configurations without specific load requirements will continue to work
>>>>>> unchanged, as init_load_uA remains zero-initialized when .init_load_uA
>>>>>> is not provided.
>>>>>
>>>>> Can we please get configuration for the rest of the platforms?
>>>>>
>>>>
>>>> Only if the rest of the platforms require setting the load... It is
>>>> not very
>>>> clear if the older platforms share the regulators with other IPs or not.
>>>
>>> Yes, they are usually shared. USB. PCIe and DSI frequently sit on the
>>> same voltage rails.
>>
>> Yes, it’s typically shared across multiple clients.
>>
>> However, as I mentioned earlier, in the current upstream codebase, the
>> "regulator-allow-set-load" property is defined only for SM8750 and SM8650
>> within the PMIC PHY and PLL device tree nodes. This means that even if the
>> UFS PHY driver is updated to vote for this configuration on other platforms,
>> it will have no effect, as the property is not supported there.
>>
> 
> Which means:
> 
> 1. Those platforms are still prone to this stability issue.
> 2. Only UFS is setting the regulator constraint, but not other drivers sharing
> the same regulator.

You understanding is correct.

> 
> IMO, both cases are bad. At leat, you can update the UFS driver to set the load
> now and later on add the DTS property as a follow-up series for those platforms.


sure will take care of this.>
> - Mani



>