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: <styd5gjksbsqt7efylpfn6bgwgyvt6zexxiooihjsnmp25yigp@unq7dor6gso2>
Date: Wed, 28 May 2025 00:10:03 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
To: 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 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.

> 
> 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
> ...
> 
> This patchset depends on [1] to allow broadcasting the type-c mode
> to the PHY, otherwise the PHY will keep the combo state while the
> retimer would setup the 4 lanes in DP mode.
> 
> [1] https://lore.kernel.org/all/20240527-topic-sm8x50-upstream-retimer-broadcast-mode-v1-0-79ec91381aba@linaro.org/
> Changes in v3:
> - Take the series from Neil
> - Rebase
> - Rename many variables
> - Test on X1E & X13s
> - Apply a number of small cosmetic/codestyle changes
> - Remove some unused variables
> - Some smaller bugfixes
> - Link to v2: https://lore.kernel.org/lkml/20240527-topic-sm8x50-upstream-phy-combo-typec-mux-v2-0-a03e68d7b8fc@linaro.org/
> Changes in v2:
> - Reference usb-switch.yaml in bindings patch
> - Fix switch/case indenting
> - Check svid for USB_TYPEC_DP_SID
> - Fix X13s patch subject
> - Update SM8650 patch to enable 4 lanes on HDK aswell
> - Link to v1: https://lore.kernel.org/r/20240229-topic-sm8x50-upstream-phy-combo-typec-mux-v1-0-07e24a231840@linaro.org
> 
> Signed-off-by: Konrad Dybcio <konrad.dybcio@....qualcomm.com>
> ---
> Konrad Dybcio (1):
>       phy: qcom: qmp-combo: Rename 'mode' to 'phy_mode'
> 
> Neil Armstrong (5):
>       dt-bindings: phy: qcom,sc8280xp-qmp-usb43dp: Reference usb-switch.yaml to allow mode-switch
>       phy: qcom: qmp-combo: store DP phy power state
>       phy: qcom: qmp-combo: introduce QMPPHY_MODE
>       phy: qcom: qmp-combo: register a typec mux to change the QMPPHY_MODE
>       arm64: dts: qcom: sc8280xp-lenovo-thinkpad-x13: Set up 4-lane DP
> 
>  .../phy/qcom,sc8280xp-qmp-usb43dp-phy.yaml         |   7 +-
>  .../dts/qcom/sc8280xp-lenovo-thinkpad-x13s.dts     |   6 +-
>  drivers/phy/qualcomm/phy-qcom-qmp-combo.c          | 182 +++++++++++++++++++--
>  3 files changed, 173 insertions(+), 22 deletions(-)
> ---
> base-commit: 460178e842c7a1e48a06df684c66eb5fd630bcf7
> change-id: 20250527-topic-4ln_dp_respin-c6924a8825ce
> 
> Best regards,
> -- 
> Konrad Dybcio <konrad.dybcio@....qualcomm.com>
> 

-- 
With best wishes
Dmitry