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671b564623
The KBD_IRQ#, SMI#, and SCI# lines on the host are sensitive to falling edges. When generating an interrupt, wait long enough to make sure the lines are high before pulling them low, so that it reliably generates a falling edge. This solves a problem where calling the IRQ-generation function twice in rapid succession could cause two low pulses without an intervening logic-high as seen by the host (and thus not a falling edge as seen by the host). This is most visible on the keyboard line, because it can generate back-to-back events on multi-byte scan codes. Once the keyboard mailbox is full, the EC will never attempt to fill it, and thus it also won't attempt to generate another keyboard IRQ. And since the host missed the IRQ, it doesn't know it needs to empty the mailbox. It could theoretically happen for the other lines, so fix them now just to be safe. This change should be low-impact and free from side effects. 4 usec is a very small additional delay. Even 65 usec added delay for SCI/SMI is small, given that SCI/SMI events are typically much less frequent (if they're happening very frequently, something else is tragically wrong with the system...) BUG=chrome-os-partner:27222 BRANCH=rambi TEST=Bang on the keyboard like a monkey. Keyboard shouldn't get stuck. Orig-Change-Id: Id4e6de793b1f007f713bac8aa195ddd78feeea3e Signed-off-by: Randall Spangler <rspangler@chromium.org> Reviewed-on: https://chromium-review.googlesource.com/193173 Reviewed-by: Duncan Laurie <dlaurie@chromium.org> Reviewed-by: Benson Leung <bleung@chromium.org> (cherry picked from commit 569651b82e309ddd86b9c165d131e34cb7f7b2b5) Change-Id: I62a9ad0fa85121b3345c057f0e3fc6b3cc29e97e Reviewed-on: https://chromium-review.googlesource.com/193174 Commit-Queue: Randall Spangler <rspangler@chromium.org> Tested-by: Randall Spangler <rspangler@chromium.org> Reviewed-by: Duncan Laurie <dlaurie@chromium.org> Reviewed-by: Benson Leung <bleung@chromium.org>