arm64: dts: mediatek: xaga: bring up USB peripheral and guarded OTG h… - #1
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This commit resolves USB device enumeration, Type-C PD negotiation,
charger BC1.2 handoff, and guarded OTG power sourcing on Xiaomi Redmi Note 11T
Pro / POCO X4 GT (xaga, MT6895):
1. MTU3 Dual-Role Controller & Peripheral Mode:
- Synchronize MTU3 internal VBUS state with external TCPM data role:
xaga lacks dedicated analog VBUS sensing routed to the MTU3 core.
Following the Xiaomi vendor MT6895 reference driver (mediatek,force-vbus):
when Type-C enters DEVICE mode, assert U3D_MISC_CTRL (VBUS_FRC_EN | VBUS_ON)
and clear SSUSB_U2_PORT_OTG_SEL to enable softconnect and D+ pullup,
allowing host computers to detect and enumerate the phone.
Safely clear force-vbus flags upon cable disconnect or host mode switch.
- Restrict role-switch userspace override on xaga to ensure only TCPM
drives role transitions without power role contention.
- Add role_lock mutex and runtime PM gating in mtu3_dr to serialize
dual-role work and unbound device recovery.
- Allow optional/missing local VBUS regulator in ssusb_set_vbus when
power is handled entirely by an external charger/TCPM supply.
2. Type-C TCPCI Controller & PD Robustness:
- In tcpci_set_polarity, use regmap_update_bits to modify the orientation
bit while preserving connection alert flags in TCPC_TCPC_CTRL.
- In tcpci_read_message, validate message byte count and header payload length
strictly. Discard malformed frames to prevent forwarding invalid zero-PDOs
to the TCPM state machine.
3. MT6375 Charger, PHY & Guarded OTG VBUS Power:
- Coordinate MT6375 BC1.2 charger detection with USB PHY switching to release
D+/D- data lines for USB transfer once detection concludes.
- Implement MT6375 OTG boost 5V supply managed strictly by TCPM, ensuring
power is sourced only after successful partner attach and role negotiation,
preventing dangerous VBUS backfeed into host ports.
- Restrict I2C bus regulator lookup in i2c-mt65xx to controller supplies.
4. Device Tree:
- Enable ssusb and usb_host in dr_mode = "otg" with peripheral default.
- Include mt6895-xaga-usb-tcpm.dtsi defining TCPC, connector, and VBUS supplies.
Tested-by: Silvia <2824799@users.noreply.github.com>
Signed-off-by: Silvia <2824799@users.noreply.github.com>
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Summary
This pull request resolves USB device/peripheral enumeration, Type-C PD negotiation, charger BC1.2 handoff, and safe OTG host power management on the Xiaomi Redmi Note 11T Pro / POCO X4 GT (
xaga, MT6895).Problem & Background
xaga, the MTU3 USB core does not have a dedicated analog VBUS sense line routed directly to the SoC. Without internal VBUS validity indication, MTU3 never initiates softconnect or pulls up the D+ line, making the device completely invisible to host PCs when plugged in via USB.tcpci_set_polaritypreviously overwroteTCPC_TCPC_CTRLviaregmap_write, unintentionally clearing the connection alert notification bit.tcpci_read_messagelacked strict header and byte count validation, which could forward corrupted packets or 0V PDOs to the TCPM state machine.Key Changes
MTU3 Dual-Role & Peripheral Mode (
drivers/usb/mtu3/):ssusb_set_device_vbus()referencing the Xiaomi MT6895 vendor BSP (mediatek,force-vbus). When TCPM signalsUSB_ROLE_DEVICE, the driver assertsU3D_MISC_CTRL (VBUS_FRC_EN | VBUS_ON)and clearsSSUSB_U2_PORT_OTG_SEL, successfully triggering high-speed device enumeration. Flags are cleanly cleared on cable disconnect or host mode.dr_workand recovery paths with arole_lockmutex and runtime PM references. Restricted userspace role overrides onxagato ensure only the hardware TCPM state machine drives transitions.ssusb_set_vbuswhen power is managed externally by the charger.TCPCI & PD Robustness (
drivers/usb/typec/tcpm/):tcpci_set_polarityto useregmap_update_bits, updating only the orientation bit while preserving connection alert flags.tcpci_read_messageto strictly validate message byte counts against PD header lengths and safely discard malformed packets.MT6375 Charger, PHY & Guarded OTG (
drivers/power/supply/mediatek/,drivers/phy/):i2c-mt65xxto controller supplies.Device Tree (
arch/arm64/boot/dts/mediatek/):ssusbandusb_hostindr_mode = "otg"withperipheraldefault.mt6895-xaga-usb-tcpm.dtsidefining the Type-C port, TCPC node, and power supplies.Hardware Validation
1d6b:0104) on PC host, stable IP communication (usb0), RDP and SSH over USB without packet drops.Tested-by: Silvia 2824799@users.noreply.github.com
Signed-off-by: Silvia 2824799@users.noreply.github.com