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

From: Neil Armstrong
Date: Wed May 29 2024 - 03:56:13 EST


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