Prevent I2C interrupts from consuming pending task events
This manifested as the lightbar task missing transitions between CPU states.
The underlying cause was that when a task talks over the I2C bus, the I2C
communication was using the task scheduler to wait for an interrupt to
signal completed I2C traffic without blocking the other threads, but while
doing so it was not preserving pending events. This CL seems to fix it.
BUG=chrome-os-partner:12431
BRANCH=all
TEST=manual
The original bug is tricky to reproduce without adding some delay to the I2C
task code, but you can do it. Boot the CPU, then from the EC console
repeatedly alternate these two commands:
lightbar seq s0
lightbar seq s3
You should see the lightbar pattern turn off and on, but occasionally you'll
type the command and the EC won't change the pattern.
With this change applied, it should *always* work.
Change-Id: Ie6819a4a36162a8760455c71c41ab8a468656af1
Signed-off-by: Bill Richardson <wfrichar@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/33805
Reviewed-by: Randall Spangler <rspangler@chromium.org>
2 files changed
