linux-kernel - Re: [PATCH V1 4/4] phy: qcom-qmp-ufs: read max-microamp values from device tree

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Message-ID: <331c5c34-9bf7-4c1f-97cb-e78749c9f6b0@quicinc.com>
Date: Tue, 12 Aug 2025 01:19:23 +0530
From: Nitin Rawat <quic_nitirawa@...cinc.com>
To: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
CC: <vkoul@...nel.org>, <kishon@...nel.org>, <mani@...nel.org>,
        <conor+dt@...nel.org>, <bvanassche@....org>, <andersson@...nel.org>,
        <neil.armstrong@...aro.org>, <konradybcio@...nel.org>,
        <krzk+dt@...nel.org>, <linux-arm-msm@...r.kernel.org>,
        <linux-phy@...ts.infradead.org>, <linux-kernel@...r.kernel.org>,
        <devicetree@...r.kernel.org>
Subject: Re: [PATCH V1 4/4] phy: qcom-qmp-ufs: read max-microamp values from
 device tree



On 8/9/2025 1:00 PM, Dmitry Baryshkov wrote:
> On Wed, Aug 06, 2025 at 09:13:40PM +0530, Nitin Rawat wrote:
>> Add support in QMP PHY driver to read optional vdda-phy-max-microamp
>> and vdda-pll-max-microamp properties from the device tree.
>>
>> These properties define the expected maximum current (in microamps) for
>> each supply. The driver uses this information to configure regulators
>> more accurately and ensure they operate in the correct mode based on
>> client load requirements.
> 
> What defines those load values? Are they actually dependent on the
> platform? On the SoC? On the board design? On the UFS gear?

Hi Dmitry,

These load values are defined at the SoC level, although they may vary 
depending on the UFS gear. However, the peak value per power grid is 
determined by the maximum gear supported by the controller.

In summary, the value is SoC-specific and does not depend on board-level 
variations. Based on this, I'm comfortable hardcoding per-compatible 
data directly in the driver instead of relying on the device tree.

Thanks,
Nitin


> 
>>
>> If the property is not present, the driver defaults load to
>> `QMP_VREG_UNUSED`.
>>
>> Signed-off-by: Nitin Rawat <quic_nitirawa@...cinc.com>
>> ---
>>   drivers/phy/qualcomm/phy-qcom-qmp-ufs.c | 22 +++++++++++++++++++---
>>   1 file changed, 19 insertions(+), 3 deletions(-)
>>
>