linux-kernel - Re: [PATCH] platform/chrome: cros_ec_typec: Set Pin Assignment E in DP PORT VDO

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Message-ID: <CAMFSARdg=p71wWoUT4G8E87bLNvxQ-JhaLbeAL6D0aUfAs-jUg@mail.gmail.com>
Date: Mon, 28 Apr 2025 08:48:22 -0700
From: Jameson Thies <jthies@...gle.com>
To: Benson Leung <bleung@...omium.org>
Cc: abhishekpandit@...omium.org, akuchynski@...omium.org, tzungbi@...nel.org, 
	chrome-platform@...ts.linux.dev, linux-kernel@...r.kernel.org, 
	sukoo@...gle.com, bleung@...gle.com
Subject: Re: [PATCH] platform/chrome: cros_ec_typec: Set Pin Assignment E in
 DP PORT VDO

On Fri, Apr 25, 2025 at 7:48 PM Benson Leung <bleung@...omium.org> wrote:
>
> Pin C and D are used on C-to-C cable applications including docks,
> and for USB-C adapters that convert from DP over USB-C to other
> video standards.
>
> Pin Assignment E is intended to be used with adapter from USB-C to DP
> plugs or receptacles.
>
> All Chromebook USB-C DFPs support DisplayPort Alternate Mode as the DP
> Source with support for all 3 pin assignments. Pin Assignment E is required
> in order to support if the user attaches a Pin E C-to-DP cable.
>
> Without this, the displayport.c alt mode driver will error out of
> dp_altmode_probe with an -ENODEV, as it cannot find a compatible matching
> pin assignment between the DFP_D and UFP_D.
>
> Signed-off-by: Benson Leung <bleung@...omium.org>

Reviewed-by: Jameson Thies <jthies@...gle.com>