msm: bam_dmux: fix ack race condition
If bam_dmux votes for A2 powerdown, and then votes for A2 powerup within
a short peroid of time, bam_dmux may intrepret the powerdown ack from A2
as the power up ack which would break the A2 PC protocol. Add an
explicit check to make sure that A2 powerup vote waits for any
previous powerdown acks.
Change-Id: I573c76034c2273da2b95891fab6a9a179bd35805
CRs-Fixed: 322305
Signed-off-by: Jeffrey Hugo <jhugo@codeaurora.org>
diff --git a/arch/arm/mach-msm/bam_dmux.c b/arch/arm/mach-msm/bam_dmux.c
index 0041f0d..b9183d2 100644
--- a/arch/arm/mach-msm/bam_dmux.c
+++ b/arch/arm/mach-msm/bam_dmux.c
@@ -194,6 +194,7 @@
static DEFINE_RWLOCK(ul_wakeup_lock);
static DECLARE_WORK(kickoff_ul_wakeup, kickoff_ul_wakeup_func);
static int bam_connection_is_active;
+static int wait_for_ack;
/* End A2 power collaspe */
/* subsystem restart */
@@ -991,6 +992,8 @@
schedule_delayed_work(&ul_timeout_work,
msecs_to_jiffies(UL_TIMEOUT_DELAY));
} else {
+ wait_for_ack = 1;
+ INIT_COMPLETION(ul_wakeup_ack_completion);
smsm_change_state(SMSM_APPS_STATE, SMSM_A2_POWER_CONTROL, 0);
bam_is_connected = 0;
notify_all(BAM_DMUX_UL_DISCONNECTED, (unsigned long)(NULL));
@@ -999,17 +1002,31 @@
}
static void ul_wakeup(void)
{
+ int ret;
+
mutex_lock(&wakeup_lock);
if (bam_is_connected) { /* bam got connected before lock grabbed */
mutex_unlock(&wakeup_lock);
return;
}
+ /*
+ * must wait for the previous power down request to have been acked
+ * chances are it already came in and this will just fall through
+ * instead of waiting
+ */
+ if (wait_for_ack) {
+ ret = wait_for_completion_interruptible_timeout(
+ &ul_wakeup_ack_completion, HZ);
+ BUG_ON(ret == 0);
+ }
INIT_COMPLETION(ul_wakeup_ack_completion);
smsm_change_state(SMSM_APPS_STATE, 0, SMSM_A2_POWER_CONTROL);
- wait_for_completion_interruptible_timeout(&ul_wakeup_ack_completion,
- HZ);
- wait_for_completion_interruptible_timeout(&bam_connection_completion,
- HZ);
+ ret = wait_for_completion_interruptible_timeout(
+ &ul_wakeup_ack_completion, HZ);
+ BUG_ON(ret == 0);
+ ret = wait_for_completion_interruptible_timeout(
+ &bam_connection_completion, HZ);
+ BUG_ON(ret == 0);
bam_is_connected = 1;
schedule_delayed_work(&ul_timeout_work,