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b81afce806
The original version of usb_upgrade does not provide for any error
recovery and also does not support any protocol version notion.
Real life experience has shown that error recovery is essential, it
needs to be introduced as a protocol enhancement. We want to stay
backwards compatible though, so there is a need for protocol
versioning.
In the original version of the protocol target response is always the
same: a 4 byte number which is the error code (and zero means no
error). This patch modifies response to the very first packet from the
host, the startup packet. The startup response is 8 bytes long. The
first 4 bytes is still the same as before, the second 4 bytes carry
the protocol version supported by the target, an integer in network
byte order.
Thus, receiving a 4 byte reply to the startup message tells the host
that the target is running protocol version zero, 8 byte reply carries
the actual version number in the last 4 bytes.
The USB transfer function on the host is enhanced to accept responses
shorter then expected, when allowed.
BRANCH=none
BUG=chrome-os-partner:52856
TEST=usb_updater can successfully update both old and new cr50 images,
properly reporting protocol version as 0 or 1 respectively.
Change-Id: I9920d2708b21f29615282161fc0eb027018f9378
Signed-off-by: Vadim Bendebury <vbendeb@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/341617
Reviewed-by: Mary Ruthven <mruthven@chromium.org>
For an overview of the Embedded Controller firmware, refer to http://www.chromium.org/chromium-os/2014-firmware-summit For instructions on building from source, refer to http://www.chromium.org/chromium-os/ec-development/getting-started-building-ec-images-quickly