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The FUSB302 will stop toggling with a FUSB_REG_STATUS1A_TOGSS_SRC? status, as soon as it sees either Ra or Rd on a CC pin. Before this commit fusb302_handle_togdone_src would assume that the toggle- engine always stopped at the CC pin indicating the polarity, IOW it assumed that it stopped at the pin connected to Rd. It did check the CC-status of that pin, but it did not expect to get a CC-status of Ra and therefore treated this as CC-open. This lead to the following 2 problems: 1) If a powered cable/adapter gets plugged in with Ra on CC1 and Rd on CC2 then 4 of 5 times when plugged in toggling will stop with a togdone_result of FUSB_REG_STATUS1A_TOGSS_SRC1. 3/5th of the time the toggle-engine is testing for being connected as a sink and after that it tests 1/5th of the time for connected as a src through CC1 before finally testing the last 1/5th of the time for being a src connected through CC2. This was a problem because we would only check the CC pin status for the pin on which the toggling stopped which in this polarity 4 out of 5 times would be the Ra pin. The code before this commit would treat Ra as CC-open and then restart toggling. Once toggling is restarted we are guaranteed to end with FUSB_REG_STATUS1A_TOGSS_SRC1 as CC1 is tested first, leading to a CC-status of Ra again and an infinite restart toggling loop. So 4 out of 5 times when plugged in in this polarity a powered adapter will not work. 2) Even if we happen to have the right polarity or 1/5th of the time in the polarity with problem 1), we would report the non Rd pin as CC-open rather then as Ra, resulting in the tcpm.c code not enabling Vconn which is a problem for some adapters. This commit fixes this by getting the CC-status of *both* pins and then determining the polarity based on that, rather then on where the toggling stopped. Signed-off-by: Hans de Goede <hdegoede@redhat.com> Acked-by: Heikki Krogerus <heikki.krogerus@linux.intel.com> Reviewed-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.