linux-kernel - Re: [PATCH RFT 2/3] arm64: dts: qcom: glymur: Add USB related nodes

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Message-ID: <86dade1c-3ac4-4352-8dc8-e7acaaf21321@oss.qualcomm.com>
Date: Tue, 27 Jan 2026 14:26:47 -0800
From: Wesley Cheng <wesley.cheng@....qualcomm.com>
To: Konrad Dybcio <konrad.dybcio@....qualcomm.com>,
        Abel Vesa <abel.vesa@....qualcomm.com>
Cc: Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konradybcio@...nel.org>, Rob Herring <robh@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Conor Dooley
 <conor+dt@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Wesley Cheng <quic_wcheng@...cinc.com>,
        Pankaj Patil <pankaj.patil@....qualcomm.com>,
        linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org
Subject: Re: [PATCH RFT 2/3] arm64: dts: qcom: glymur: Add USB related nodes



On 1/27/2026 3:46 AM, Konrad Dybcio wrote:
> On 1/27/26 12:41 PM, Abel Vesa wrote:
>> On 26-01-13 14:13:32, Konrad Dybcio wrote:
>>> On 1/13/26 1:33 PM, Abel Vesa wrote:
>>>> From: Wesley Cheng <wesley.cheng@....qualcomm.com>
>>>>
>>>> The Glymur USB system contains 3 USB type C ports, 1 USB multiport
>>>> controller and a USB 2.0 only controller. This encompasses 5 SS USB QMP
>>>> PHYs (3 combo and 2 uni) and 6 M31 eUSB2 PHYs. All controllers are SNPS
>>>> DWC3 based, so describe them as flattened DWC3 QCOM nodes.
>>>>
>>>> Signed-off-by: Wesley Cheng <wesley.cheng@....qualcomm.com>
>>>> Co-developed-by: Abel Vesa <abel.vesa@....qualcomm.com>
>>>> Signed-off-by: Abel Vesa <abel.vesa@....qualcomm.com>
>>>> ---
>>>
>>> [...]
>>>
>>>> +			snps,dis_u2_susphy_quirk;
>>>> +			snps,dis_enblslpm_quirk;
>>>> +			snps,dis_u3_susphy_quirk;
>>>> +			snps,usb2-lpm-disable;
>>>
>>> Other SoCs have a list that's much longer, please consult Wesley if
>>> this list is enough
>>
>> Checked with Wesley. He confirmed that this trimmed list is fine.
>> He said he dropped the rest since they are related to the power saving
>> features like USB2/3 LPM (l1 or u1/u2) and we don't seem need those.
> 
> Is that to say that those erratas were fixed in this hardware?
> 
> Low-power states of the link are no less than desired is possible..
> 

I think it was misunderstood.  We should keep the same quirks as our 
previous targets to enable USB LPM support in certain cases.

snps,hird-threshold = /bits/ 8 <0x0>;
snps,usb2-gadget-lpm-disable;
snps,dis-u1-entry-quirk;
snps,dis-u2-entry-quirk;
snps,is-utmi-l1-suspend;
snps,usb3_lpm_capable;
snps,has-lpm-erratum;
tx-fifo-resize;
snps,dis_u2_susphy_quirk;
snps,dis_enblslpm_quirk;
snps,usb2-lpm-disable;

There are some questionable ones that I'm on the fence though, which we 
should consider removing:
snps,usb2-lpm-disable
snps,usb2-gadget-lpm-disable

USB L1 support is routinely being verified on our devices (in host and 
device modes), so if its power over performance, we should consider 
removing the properties to disable USB L1. (esp since we're defining the 
HIRD threshold as well...)

Thanks
Wesley Cheng