USB: EHCI: improve end_unlink_async()
This patch (as1665) changes the way ehci-hcd's end_unlink_async()
routine works in order to avoid recursive execution and to be more
efficient:
Now when an IAA cycle ends, a new one gets started up right
away (if it is needed) instead of waiting until the
just-unlinked QH has been processed.
The async_iaa list is renamed to async_idle, which better
expresses its new purpose: It is now the list of QHs which are
now completely idle and are waiting to be processed by
end_unlink_async().
A new flag is added to track whether an IAA cycle is in
progress, because the list formerly known as async_iaa no
longer stores the QHs waiting for the IAA to finish.
The decision about how many QHs to process when an IAA cycle
ends is now made at the end of the cycle, when we know the
current state of the hardware, rather than at the beginning.
This means a bunch of logic got moved from start_iaa_cycle()
to end_unlink_async().
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/usb/host/ehci.h b/drivers/usb/host/ehci.h
index 13f6704..e666999 100644
--- a/drivers/usb/host/ehci.h
+++ b/drivers/usb/host/ehci.h
@@ -121,6 +121,7 @@
bool scanning:1;
bool need_rescan:1;
bool intr_unlinking:1;
+ bool iaa_in_progress:1;
bool async_unlinking:1;
bool shutdown:1;
struct ehci_qh *qh_scan_next;
@@ -129,7 +130,7 @@
struct ehci_qh *async;
struct ehci_qh *dummy; /* For AMD quirk use */
struct list_head async_unlink;
- struct list_head async_iaa;
+ struct list_head async_idle;
unsigned async_unlink_cycle;
unsigned async_count; /* async activity count */