linux-kernel - Re: [PATCH v2 0/7] arm64: qcom: allow up to 4 lanes for the Type-C DisplayPort Altmode

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Message-ID: <b738eece-2169-44d8-a9dc-9031c6d9a175@linaro.org>
Date: Wed, 29 May 2024 09:55:55 +0200
From: Neil Armstrong <neil.armstrong@...aro.org>
To: Bjorn Andersson <andersson@...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>, Konrad Dybcio <konrad.dybcio@...aro.org>,
 Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
 linux-arm-msm@...r.kernel.org, linux-phy@...ts.infradead.org,
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 0/7] arm64: qcom: allow up to 4 lanes for the Type-C
 DisplayPort Altmode

On 28/05/2024 15:48, Bjorn Andersson wrote:
> On Mon, May 27, 2024 at 10:42:32AM GMT, Neil Armstrong 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.
>>
>> The Type-C Mode/SVID only changes on plug/unplug, and USB SAFE states
>> will be set in between of USB-Only, Combo and DisplayPort Only so
>> this will leave enough time to the DRM DisplayPort controller to
>> turn of the DisplayPort PHY.
>>
>> The patchset also includes bindings changes and DT changes.
>>
>> This has been successfully tested on an SM8550 board, but the
>> Thinkpad X13s deserved testing between non-PD USB, non-PD DisplayPort,
>> PD USB Hubs and PD Altmode Dongles to make sure the switch works
>> as expected.
>>
>> The DisplayPort 4 lanes setup can be check with:
>> $ cat /sys/kernel/debug/dri/ae01000.display-controller/DP-1/dp_debug
>> 	name = msm_dp
>> 	drm_dp_link
>> 		rate = 540000
>> 		num_lanes = 4
> 
> Has the issue with the USB controller dying on us been resolved?

No, this would require some changes in dwc3 & ucsi to support the USB_ROLE_NONE

I haven't looked into this yet.

Neil

> 
> Regards,
> Bjorn