On Thu, 18 Oct 2012, Peter Chen wrote:
> > I decided to use a different approach. The core should know which
> > ports are suspended without asking the HCD. Can you test this patch in
> > place of the other one?
> It shows below oops, you may not consider there is no device at port
> condition.
Quite right. I consider this to be a bug in hub_for_each_child; the
first patch below fixes that bug.
> Besides, how about using usleep_range instead of msleep? msleep is not
> precise, and should not be used at (<20ms) condition, at my platform,
> msleep 10 consumes about 19-20ms.
Good idea; the second patch below is updated to use usleep_range
instead of msleep. These two patches together should do what you want.
Alan Stern
First patch: Fix hub_for_each_child
Index: usb-3.6/include/linux/usb.h
===================================================================
--- usb-3.6.orig/include/linux/usb.h
+++ usb-3.6/include/linux/usb.h
@@ -588,8 +588,9 @@ extern struct usb_device *usb_hub_find_c
*/
#define usb_hub_for_each_child(hdev, port1, child) \
for (port1 = 1, child = usb_hub_find_child(hdev, port1); \
- port1 <= hdev->maxchild; \
- child = usb_hub_find_child(hdev, ++port1))
+ port1 <= hdev->maxchild; \
+ child = usb_hub_find_child(hdev, ++port1)) \
+ if (!child) continue; else
/* USB device locking */
#define usb_lock_device(udev) device_lock(&(udev)->dev)
Second patch: Speed up bus resumes
Index: usb-3.6/include/linux/usb.h
===================================================================
--- usb-3.6.orig/include/linux/usb.h
+++ usb-3.6/include/linux/usb.h
@@ -482,6 +482,7 @@ struct usb3_lpm_parameters {
* @connect_time: time device was first connected
* @do_remote_wakeup: remote wakeup should be enabled
* @reset_resume: needs reset instead of resume
+ * @port_is_suspended: the upstream port is suspended (L2 or U3)
* @wusb_dev: if this is a Wireless USB device, link to the WUSB
* specific data for the device.
* @slot_id: Slot ID assigned by xHCI
@@ -560,6 +561,7 @@ struct usb_device {
unsigned do_remote_wakeup:1;
unsigned reset_resume:1;
+ unsigned port_is_suspended:1;
#endif
struct wusb_dev *wusb_dev;
int slot_id;
Index: usb-3.6/drivers/usb/core/hub.c
===================================================================
--- usb-3.6.orig/drivers/usb/core/hub.c
+++ usb-3.6/drivers/usb/core/hub.c
@@ -2876,6 +2876,7 @@ int usb_port_suspend(struct usb_device *
(PMSG_IS_AUTO(msg) ? "auto-" : ""),
udev->do_remote_wakeup);
usb_set_device_state(udev, USB_STATE_SUSPENDED);
+ udev->port_is_suspended = 1;
msleep(10);
}
usb_mark_last_busy(hub->hdev);
@@ -3040,6 +3041,7 @@ int usb_port_resume(struct usb_device *u
SuspendCleared:
if (status == 0) {
+ udev->port_is_suspended = 0;
if (hub_is_superspeed(hub->hdev)) {
if (portchange & USB_PORT_STAT_C_LINK_STATE)
clear_port_feature(hub->hdev, port1,
Index: usb-3.6/drivers/usb/core/hcd.c
===================================================================
--- usb-3.6.orig/drivers/usb/core/hcd.c
+++ usb-3.6/drivers/usb/core/hcd.c
@@ -2039,8 +2039,9 @@ int hcd_bus_resume(struct usb_device *rh
status = hcd->driver->bus_resume(hcd);
clear_bit(HCD_FLAG_WAKEUP_PENDING, &hcd->flags);
if (status == 0) {
- /* TRSMRCY = 10 msec */
- msleep(10);
+ struct usb_device *udev;
+ int port1;
+
spin_lock_irq(&hcd_root_hub_lock);
if (!HCD_DEAD(hcd)) {
usb_set_device_state(rhdev, rhdev->actconfig
@@ -2050,6 +2051,20 @@ int hcd_bus_resume(struct usb_device *rh
hcd->state = HC_STATE_RUNNING;
}
spin_unlock_irq(&hcd_root_hub_lock);
+
+ /*
+ * Check whether any of the enabled ports on the root hub are
+ * unsuspended. If they are then a TRSMRCY delay is needed
+ * (this is what the USB-2 spec calls a "global resume").
+ * Otherwise we can skip the delay.
+ */
+ usb_hub_for_each_child(rhdev, port1, udev) {
+ if (udev->state != USB_STATE_NOTATTACHED &&
+ !udev->port_is_suspended) {
+ usleep_range(10000, 11000); /* TRSMRCY */
+ break;
+ }
+ }
} else {
hcd->state = old_state;
dev_dbg(&rhdev->dev, "bus %s fail, err %d\n",
--
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