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Date:   Wed, 28 Oct 2020 10:10:43 +0100
From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     Benjamin Berg <benjamin@sipsolutions.net>
Cc:     linux-usb@vger.kernel.org, Guenter Roeck <linux@roeck-us.net>,
        linux-kernel@vger.kernel.org, Benjamin Berg <bberg@redhat.com>,
        Hans de Goede <hdegoede@redhat.com>,
        Heikki Krogerus <heikki.krogerus@linux.intel.com>
Subject: Re: [PATCH 0/2] UCSI race condition resulting in wrong port state
Message-ID: <20201028091043.GC1947336@kroah.com>
References: <20201009144047.505957-1-benjamin@sipsolutions.net>
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On Fri, Oct 09, 2020 at 04:40:45PM +0200, Benjamin Berg wrote:
> From: Benjamin Berg <bberg@redhat.com>
> 
> Hi all,
> 
> so, I kept running in an issue where the UCSI port information was saying
> that power was being delivered (online: 1), while no cable was attached.
> 
> The core of the problem is that there are scenarios where UCSI change
> notifications are lost. This happens because querying the changes that
> happened is done using the GET_CONNECTOR_STATUS command while clearing the
> bitfield happens from the separate ACK command. Any change in between will
> be lost.
> 
> Note that the problem may be almost invisible in the UI as e.g. GNOME will
> still show the battery as discharging. But some policies like automatic
> suspend may be applied incorrectly.
> 
> Cc: Hans de Goede <hdegoede@redhat.com>
> Cc: Heikki Krogerus <heikki.krogerus@linux.intel.com>
> 
> Benjamin Berg (2):
>   usb: typec: ucsi: acpi: Always decode connector change information
>   usb: typec: ucsi: Work around PPM losing change information

Do these need to be backported to stable kernel releases?  If so, how
far back?

thjanks,

greg k-h