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c4383ca93f
If a key is pressed which is not in actual_key_mask, this triggers the
keyboard scan interrupt. But read_matrix() would use the key mask to
decide that no *real* keys were pressed. So it would immediately drop
out of scan mode back to interrupt mode. Which would again be
triggered. Lather, rinse, repeat, watchdog.
The fix is to use the unmasked key matrix to decide whether to stay in
scan mode. This way, the keyboard task sleeps between scans, and the
watchdog isn't triggered.
(Note that the only way you can hit this bug in real life is to have a
keyboard attached which can trigger keys not in actual_key_mask.
Which is hard to do, unless you've got a new prototype keyboard with
extra keys, or you've spilled lemon juice on your Chromebook...)
BUG=chrome-os-partner:25333
BRANCH=rambi
TEST=Zero out actual_key_mask in keyboard_scan.c. Press a key. Should
not trigger a watchdog.
Change-Id: I8c2fbc3e06fa12dfae5c06614814af8f04e24a8a
Signed-off-by: Randall Spangler <rspangler@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/184323
Reviewed-by: Dave Parker <dparker@chromium.org>
Tested-by: Dave Parker <dparker@chromium.org>
In the most general case, the flash layout looks something like this: +---------------------+ | Reserved for EC use | +---------------------+ +---------------------+ | Vblock B | +---------------------+ | RW firmware B | +---------------------+ +---------------------+ | Vblock A | +---------------------+ | RW firmware A | +---------------------+ +---------------------+ | FMAP | +---------------------+ | Public root key | +---------------------+ | Read-only firmware | +---------------------+ BIOS firmware (and kernel) put the vblock info at the start of each image where it's easy to find. The Blizzard EC expects the firmware vector table to come first, so we have to put the vblock at the end. This means we have to know where to look for it, but that's built into the FMAP and the RO firmware anyway, so that's not an issue. The RO firmware doesn't need a vblock of course, but it does need some reserved space for vboot-related things. Using SHA256/RSA4096, the vblock is 2468 bytes (0x9a4), while the public root key is 1064 bytes (0x428) and the current FMAP is 644 bytes (0x284). If we reserve 4K at the top of each FW image, that should give us plenty of room for vboot-related stuff.