ipmi: flush the ipmi message queue before booting a kernel

Bring ipmi to a consistent state before booting a kernel by flushing
all outstanding messages. The OS may not start kicking the IPMI state
machine for some time.

For example, without this change, when booting in QEMU, the IPMI command
issued by ipmi_wdt_final_reset() to disable the watchdog is not sent to
the BMC before the OS boots, effectively leaving the watchdog enabled
until the OS begins to drive OPAL pollers.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Stewart Smith <stewart@flamingspork.com>
Signed-off-by: Reza Arbab <arbab@linux.ibm.com>

1 files changed, 6 insertions, 1 deletions

diff --git a/hw/bt.c b/hw/bt.c
index 5016fea..1912cd3 100644
--- a/hw/bt.c
+++ b/hw/bt.c
@@ -519,9 +519,14 @@ static void bt_poll(struct timer *t __unused, void *data __unused,
 		       bt.irq_ok ? TIMER_POLL : msecs_to_tb(BT_DEFAULT_POLL_MS));
 }
 
-static void bt_ipmi_poll(void)
+static bool bt_ipmi_poll(void)
 {
+	if (!lpc_ok())
+		return false;
+
 	bt_poll(NULL, NULL, mftb());
+
+	return bt.queue_len > 0;
 }
 
 static void bt_add_msg(struct bt_msg *bt_msg)