Adjust the fdc worker thread startup to work when APs are started earlier.

- Enable the commented out locking in fd_probe().  The worker thread
  should not be running yet (even after these changes), but better to be
  safe than sorry.
- Defer starting the worker thread until after the child drives have been
  probed.  The worker thread startup is moved into a fdc_start_worker()
  thread that the various front ends call at the end of attach.  As a
  side effect this fixes a few edge cases that weren't shutting down the
  worker thread if attach encountered a late failure.
- When executing the initial reset requested by attach in the worker
  thread, use DELAY() instead of a tsleep() if cold is set.

Tested by:	Howard Su <howard0su@gmail.com>
Sponsored by:	Netflix

1 files changed, 3 insertions, 1 deletions

diff --git a/sys/dev/fdc/fdc_cbus.c b/sys/dev/fdc/fdc_cbus.c
index ee1598dccb07..b03b370375d8 100644
--- a/sys/dev/fdc/fdc_cbus.c
+++ b/sys/dev/fdc/fdc_cbus.c
@@ -150,7 +150,9 @@ fdc_cbus_attach(device_t dev)
 		error = fdc_attach(dev);
 	if (error == 0)
 		error = fdc_hints_probe(dev);
-	if (error)
+	if (error == 0)
+		fdc_start_worker(dev);
+	else
 		fdc_release_resources(fdc);
 	return (error);
 }