Some laptops have weak power controllers that cannot tolerate multiple

cards powering up at once.  Work around the easy case (multiple cards
inserted on boot) with a short sleep and a long comment.  This
improves reliability on those laptops with power hungry cards.

1 files changed, 7 insertions, 0 deletions

diff --git a/sys/dev/pccbb/pccbb.c b/sys/dev/pccbb/pccbb.c
index b116b54de503..cd3e3cf6ede0 100644
--- a/sys/dev/pccbb/pccbb.c
+++ b/sys/dev/pccbb/pccbb.c
@@ -460,6 +460,13 @@ cbb_event_thread(void *arg)
 	int err;
 	int not_a_card = 0;
 
+	/*
+	 * We need to act as a power sequencer on startup.  Delay 2s/channel
+	 * to ensure the other channels have had a chance to come up.  We likely
+	 * should add a lock that's shared on a per-slot basis so that only
+	 * one power event can happen per slot at a time.
+	 */
+	pause("cbbstart", hz * device_get_unit(sc->dev) * 2);
 	mtx_lock(&sc->mtx);
 	sc->flags |= CBB_KTHREAD_RUNNING;
 	while ((sc->flags & CBB_KTHREAD_DONE) == 0) {