Re: [PATCH v5 6/9] dt/bindings: drm/bridge: it6505: Add mode-switch support

[Prashant Malani]

On Thu, Jun 23, 2022 at 11:24 AM Stephen Boyd <swboyd@xxxxxxxxxxxx> wrote:
>
> Quoting Prashant Malani (2022-06-22 10:34:35)
> > From: Pin-Yen Lin <treapking@xxxxxxxxxxxx>
> >
> > ITE IT6505 can be used in systems to switch USB Type-C DisplayPort
> > alternate mode lane traffic between 2 Type-C ports.
>
> How does it work? From what I can tell from the information I find when
> googling this part[1] and looking at the existing binding doc is that
> this device is a DPI to DP bridge, and it outputs DP (probably 4 lanes
> of it?). Does the 2 type-c port design work by transmitting DP on two
> lanes of DP for one type-c port and another two lanes of DP for the
> other type-c port?
>
> DP could be one lane, so if this device is able to output one lane on
> any output differential pair then I suspect it could support 4 type-c
> ports if the hardware engineer connected it that way. Can you confirm my
> suspicion?

I will let Pin-Yen comment re: this hardware, but 1-lane DP is not a
supported Type-C Pin assignment
(as per VESA DP Alternate Mode Spec version 2.0 [2]), so the H/W
configuration you are suggesting shouldn't be possible.

>
> [1] https://www.ite.com.tw/en/product/view?mid=45