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

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Message-ID: <5a773b89-f3f8-486b-af01-3387c99e53e5@oss.qualcomm.com>
Date: Wed, 28 Jan 2026 10:53:35 +0100
From: Konrad Dybcio <konrad.dybcio@....qualcomm.com>
To: Wesley Cheng <wesley.cheng@....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 1/27/26 11:26 PM, Wesley Cheng wrote:
> 
> 
> 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.

Does the fact that we allow L1 entry impact performance itself, or is
there some room for improvement in the drivers?


 (esp since we're defining the HIRD threshold as well...)

Wouldn't HIRD threshold be related to *U*1(/2) though?
I see in the list above you decalred

snps,dis-u1-entry-quirk
snps,dis-u2-entry-quirk

which forbid them

and the threshold is set to 0, so IIUC that means entry is only allowed
for devices that don't ""really"" suspend

Konrad