[SeaBIOS] [PATCH] ps2: Disable keyboard and mouse before flushing the queue

[Paul Menzel]

From: Stefan Reinauer

If SeaBIOS is run as a payload via coreboot (and presumably as a
CSM), then it's possible the keyboard or mouse will still be
enabled.  This can lead to data being queued even after the flush
function attempts to clear the queue.

Disabling the keyboard/mouse prior to flushing is pretty standard
in DOS programming so it's not surprising that it's needed here.

I believe this problem manifests with the Chromebook Pixel.  People
have reported that sometimes the 'ESC to Select Boot Devices'
doesn't work.  I can reproduce this faithfully by holding 'Ctrl-L'
in the firmware screen during SeaBIOS initialization.

I can't test this fix on an actual Pixel because I don't know how
to update SeaBIOS but I have tested the patch under QEMU.

BUG=none
TEST=Boot into SeaBIOS, press ESC, see it working.

Change-Id: I4e74a559e86539730f4fda1d429612c759da16ee
Signed-off-by: Anthony Liguori 
Signed-off-by: Stefan Reinauer 
Reviewed-on: https://gerrit.chromium.org/gerrit/49212
Reviewed-by: Ronald G. Minnich 
Cc: Matt DeVillier 
Signed-off-by: Paul Menzel 
---
 src/hw/ps2port.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/hw/ps2port.c b/src/hw/ps2port.c
index 9b099e8..c99ea54 100644
--- a/src/hw/ps2port.c
+++ b/src/hw/ps2port.c
@@ -58,6 +58,12 @@ static int
 i8042_flush(void)
 {
     dprintf(7, "i8042_flush\n");
+
+    /* Disable the keyboard and mouse to prevent additional data from
+     * being queued. */
+    outb(0xad, PORT_PS2_STATUS);
+    outb(0xa7, PORT_PS2_STATUS);
+
     int i;
     for (i=0; i<I8042_BUFFER_SIZE; i++) {
         u8 status = inb(PORT_PS2_STATUS);