linux-kernel - Re: [PATCH v3 0/6] arm64: qcom: allow up to 4 lanes for the Type-C DisplayPort Altmode

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Message-ID: <447c3b13-8d6d-4bcb-83c1-9456b915a77e@oss.qualcomm.com>
Date: Wed, 28 May 2025 00:24:02 +0200
From: Konrad Dybcio <konrad.dybcio@....qualcomm.com>
To: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>,
        Konrad Dybcio <konradybcio@...nel.org>
Cc: Vinod Koul <vkoul@...nel.org>, Kishon Vijay Abraham I
 <kishon@...nel.org>,
        Rob Herring <robh@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Conor Dooley
 <conor+dt@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Marijn Suijten <marijn.suijten@...ainline.org>,
        linux-arm-msm@...r.kernel.org, linux-phy@...ts.infradead.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        Konrad Dybcio <konrad.dybcio@....qualcomm.com>,
        Neil Armstrong <neil.armstrong@...aro.org>,
        Krzysztof Kozlowski <krzk@...nel.org>
Subject: Re: [PATCH v3 0/6] arm64: qcom: allow up to 4 lanes for the Type-C
 DisplayPort Altmode

On 5/27/25 11:10 PM, Dmitry Baryshkov wrote:
> On Tue, May 27, 2025 at 10:40:02PM +0200, Konrad Dybcio wrote:
>> Register a typec mux in order to change the PHY mode on the Type-C
>> mux events depending on the mode and the svid when in Altmode setup.
>>
>> The DisplayPort phy should be left enabled if is still powered on
>> by the DRM DisplayPort controller, so bail out until the DisplayPort
>> PHY is not powered off.
> 
> This series doesn't seem to solve the USB side of a problem. When the
> PHY is being switch to the 4-lane mode, USB controller looses PIPE
> clock, so it needs to be switched to the USB-2 mode.

I didn't find issues with that on X13s.. Not sure if it's related, but
on the SL7, after plugging in a 4ln DP connection, I need to plug in
the USB thumb drive twice for the first time (only in that sequence)

But there's nothing interesting in dmesg and the phy seems to be
programmed with the same values on both the initial and the subsequent
working plug-in

Konrad