cros_ec: Retry failed VBNV transactions

This patch adds a few retries to NVRAM read/write transactions with the
EC. Failing to read the NVRAM is not fatal to the boot, but it's still
pretty bad... especially since a single initial read failure will cause
vboot to blindly reinitialize the whole NVRAM with zeroes, destroying
important configuration bits like dev_boot_usb. The current EC
transaction timeout is one second, so the three retries added here can
potentially increase boot time by three seconds per transaction... but
this shouldn't happen in any normal case anyway, and if there are errors
a little extra wait is probably preferrable to nuking your NVRAM.

(Also, added a missing newline to an error message in the EC code.)

BRANCH=veyron
BUG=chrome-os-partner:36924
TEST=Booted a Jerry with the power button bug with a 2 second press,
noticed that the first two transactions failed but the third one
succeeded.

Change-Id: I5d1cf29ac1c555ea2336ebb0b0e0a3f7cbb9c3fd
Signed-off-by: Stefan Reinauer <reinauer@chromium.org>
Original-Commit-Id: 894a8a0b4a9805e92544b5e3dfa90baf6d36649a
Original-Change-Id: I6267cdda2be2bad34541b687404c2434d3be345b
Original-Signed-off-by: Julius Werner <jwerner@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/251694
Original-Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: http://review.coreboot.org/9507
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <pgeorgi@google.com>

0 files changed, 0 insertions, 0 deletions