Re: [PATCH v2] phy: qcom: qmp-combo: Leave the USB PCS alone in DP-only mode

[Abel Vesa]

On 26-10-23 21:35:12, Joonhoe Kim wrote:
> In DP-only mode (DisplayPort pin assignments C and E) all four lanes
> belong to the DisplayPort PHY and the USB PCS stays powered down.
> Three paths still touch the USB PCS in this state:
> 
> - The USB controller can exit and re-init its PHY in DP-only mode, e.g.
>   across a system suspend that loses power. qmp_combo_usb_init() then
>   programs the USB serdes, lane and PCS tables over the DisplayPort
>   configuration and times out waiting for PHYSTATUS, and
>   qmp_combo_usb_exit() resets and powers down a PCS that is not in use.
> - qmp_combo_typec_switch_set() powers the USB PCS off and on when the
>   orientation changes in DP-only mode, e.g. when a DP-only sink is
>   plugged in the other way round while the mux is still in DP-only
>   mode.
> - qmp_combo_reconfigure_phy() powers the USB PCS off again when the
>   port leaves DP-only mode.
> 
> Skip the USB PCS in these paths in DP-only mode. Keep the
> qmp_combo_com_init()/qmp_combo_com_exit() reference and usb_init_count,
> so that qmp_combo_reconfigure_phy() powers the USB PCS up when the port
> leaves DP-only mode.
> 
> On a Lenovo Y700 Gen 5 (TB323FU, Kaanapali) with a USB-C monitor
> in pin assignment C, resume from s2idle fails with "phy initialization
> timed-out", the dwc3 resume returns -110 and the following xHCI resume
> hangs the system.
> 
> Fixes: 896277138c13 ("phy: qcom: qmp-combo: register a typec mux to change the QMPPHY_MODE")
> Fixes: 89563a152973 ("phy: qualcomm: qmp-combo: Add preliminary USB4 support")
> Signed-off-by: Joonhoe Kim <26rote@xxxxxxxxx>

Reviewed-by: Abel Vesa <abel.vesa@xxxxxxxxxxxxxxxx>