linux-kernel - Re: [PATCH v5 1/3] usb: typec: tcpm: Add callbacks to mitigate wakeups due to contaminant

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Message-ID: <CAPTae5KmmYoxcQWGC7yBjyZYqZn7PXLdN4jag=5Zv0RAqYyu_g@mail.gmail.com>
Date:   Thu, 8 Dec 2022 07:06:10 -0800
From:   Badhri Jagan Sridharan <badhri@...gle.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Guenter Roeck <linux@...ck-us.net>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        Kyle Tso <kyletso@...gle.com>
Subject: Re: [PATCH v5 1/3] usb: typec: tcpm: Add callbacks to mitigate
 wakeups due to contaminant

Apologies ! fixed it in Version 6.

On Wed, Dec 7, 2022 at 11:03 PM Greg Kroah-Hartman
<gregkh@...uxfoundation.org> wrote:
>
> On Wed, Dec 07, 2022 at 06:00:41PM -0800, Badhri Jagan Sridharan wrote:
> > On some of the TCPC implementations, when the Type-C port is exposed
> > to contaminants, such as water, TCPC stops toggling while reporting OPEN
> > either by the time TCPM reads CC pin status or during CC debounce
> > window. This causes TCPM to be stuck in TOGGLING state. If TCPM is made
> > to restart toggling, the behavior recurs causing redundant CPU wakeups
> > till the USB-C port is free of contaminant.
> >
> > [206199.287817] CC1: 0 -> 0, CC2: 0 -> 0 [state TOGGLING, polarity 0, disconnected]
> > [206199.640337] CC1: 0 -> 0, CC2: 0 -> 0 [state TOGGLING, polarity 0, disconnected]
> > [206199.985789] CC1: 0 -> 0, CC2: 0 -> 0 [state TOGGLING, polarity 0, disconnected]
> > ...
> >
> > TCPM invokes is_potential_contaminant callback to allow low level chip
> > drivers to monitor TCPM state machine transitions and notify TCPM when
> > the Type-C port needs to be checked for potential contaminant presence.
> > TCPCs which do have the needed hardware can implement the check_contaminant
> > callback which is invoked by TCPM to evaluate for presence of contaminant.
> > Lower level TCPC driver can restart toggling through TCPM_PORT_CLEAN event
> > when the driver detects that USB-C port is free of contaminant.
> >
> > Signed-off-by: Badhri Jagan Sridharan <badhri@...gle.com>
> > Change-Id: I136d788bb46d871d12e64bd73fd50a77b4659dbf
> > ---
>
> Always run checkpatch.pl on your patches so you don't get a grumpy
> maintainer asking why you didn't run checkpatch.pl on your patches :(