linux-kernel - Re: [PATCH v5 5/9] drm/bridge: anx7625: Add typec_mux

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Message-ID: <CAE-0n50Akd8QikGhaAQgxLkJBhE-7KQf5aJ_P2ajOmCjLk555g@mail.gmail.com>
Date:   Thu, 30 Jun 2022 16:21:40 -0700
From:   Stephen Boyd <swboyd@...omium.org>
To:     Prashant Malani <pmalani@...omium.org>
Cc:     linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org,
        bleung@...omium.org, heikki.krogerus@...ux.intel.com,
        Pin-Yen Lin <treapking@...omium.org>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>,
        Nícolas F . R . A . Prado 
        <nfraprado@...labora.com>, Allen Chen <allen.chen@....com.tw>,
        Andrzej Hajda <andrzej.hajda@...el.com>,
        Daniel Vetter <daniel@...ll.ch>,
        David Airlie <airlied@...ux.ie>, devicetree@...r.kernel.org,
        dri-devel@...ts.freedesktop.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Hsin-Yi Wang <hsinyi@...omium.org>,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        Jonas Karlman <jonas@...boo.se>,
        José Expósito <jose.exposito89@...il.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        Maxime Ripard <maxime@...no.tech>,
        Neil Armstrong <narmstrong@...libre.com>,
        Robert Foss <robert.foss@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Sam Ravnborg <sam@...nborg.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        Xin Ji <xji@...logixsemi.com>
Subject: Re: [PATCH v5 5/9] drm/bridge: anx7625: Add typec_mux_set callback function

Quoting Prashant Malani (2022-06-28 13:56:22)
> On Tue, Jun 28, 2022 at 1:40 PM Stephen Boyd <swboyd@...omium.org> wrote:
> >
> > I suppose none of those things matter though as long as there is some
> > typec switch registered here so that the driver can be informed of the
> > pin assignment. Is it right that the "mode-switch" property is only
> > required in DT if this device is going to control the mode of the
> > connector, i.e. USB+DP, or just DP? Where this device can't do that
> > because it doesn't support only DP.
>
> If the anx7625 is used just to route all lanes from 1 usb-c-connector (i.e
> the USB+DP case), a mode-switch wouldn't be of much use, since one
> would also route the CC lines to the built-in PD controller; so it will
> already have knowledge of what mode the switch is in.
>
> The mode-switch is likely only relevant for this hardware configuration(
> it's "DP only" in the sense that the USB pins to the SoC never go anywhere).
> One only has 2 SS lanes each (from each usb-c-connector).
>
> Since there is no CC-line, the anx7625 needs to know which one has DP
> enabled on it.

Can the CC line be "captured" and not actually sent to the anx7625? I
imagine if that is possible, maybe the CC lines would go to some
micro-controller or something that did more typec management things and
then the anx7625 driver would need to do software control of the mode
and orientation control.