Re: [PATCH v2 2/2] phy: rockchip: usbdp: re-init the phy on orientation-change

[Quentin Schulz <quentin.schulz@cherry.de>]

Hi Sebastian,

On 3/1/25 10:19 PM, Sebastian Reichel wrote:
> Hello Quentin,
> 
> On Wed, Feb 26, 2025 at 01:38:10PM +0100, Quentin Schulz wrote:
>> Unrelated to this patch (but may be triggered by this patch?), I'm wondering
>> how flip is really handled.
>>
>> It seems like we have flip store the orientation of the cable, but also if
>> rockchip,dp-lane-mux is set to <0 1>. But wouldn't that break if we ignore
>> that initial flipped lane-mux whenever a USB-C cable is inserted in reverse?
>> Basically, shouldn't a reserve orientation of the cable when
>> rockchip,dp-lane-mux is set to <0 1> mean "normal mux"?
> 
> If a USB-C connector is involved, the TypeC controller is supposed to
> setup the lane muxing based on the connector orientation. This
> happens via the typec API and in this hardware setup the PHY should
> not have the rockchip,dp-lane-mux DT property set.
> 

I could see some HW routing "mistake" where the USB-C connector in 
normal orientation has DP lanes routed to RX1/TX1? Or is this expected 
to just be faulty HW we shouldn't attempt at supporting?

> The rockchip,dp-lane-mux property is required if no USB-C connector
> is involved. For example if the lanes are routed to a Displayport
> connector. In that case the lane setup is fixed in hardware and
> there is no TypeC controller involved, which could do any setup ;)
> 

Yup I've seen that for the Rock 5 ITX and the evaluation board(s) do 
this. Quite interesting :)

Cheers,
Quentin