From: Alan Stern <st...@rowland.harvard.edu>
The USB core doesn't properly handle mutual exclusion between
resetting a hub and changing the power states of the hub's ports. We
need to avoid sending port-power requests to the hub while it is being
reset, because such requests cannot succeed.
This patch fixes the problem by keeping track of when a reset is in
progress. At such times, attempts to suspend (power-off) a port will
fail immediately with -EBUSY, and calls to usb_port_runtime_resume()
will update the power_is_on flag and return immediately. When the
reset is complete, hub_activate() will automatically restore each port
to the proper power state.
Signed-off-by: Alan Stern <st...@rowland.harvard.edu>
Signed-off-by: Dan Williams <dan.j.willi...@intel.com>
---
drivers/usb/core/hub.c | 12 ++++++++++++
drivers/usb/core/hub.h | 1 +
drivers/usb/core/port.c | 6 ++++++
3 files changed, 19 insertions(+), 0 deletions(-)
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 090469ebfcff..e3bc03ee0928 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -1276,12 +1276,22 @@ static void hub_quiesce(struct usb_hub *hub, enum
hub_quiescing_type type)
flush_work(&hub->tt.clear_work);
}
+static void hub_pm_barrier_for_all_ports(struct usb_hub *hub)
+{
+ int i;
+
+ for (i = 0; i < hub->hdev->maxchild; ++i)
+ pm_runtime_barrier(&hub->ports[i]->dev);
+}
+
/* caller has locked the hub device */
static int hub_pre_reset(struct usb_interface *intf)
{
struct usb_hub *hub = usb_get_intfdata(intf);
hub_quiesce(hub, HUB_PRE_RESET);
+ hub->in_reset = 1;
+ hub_pm_barrier_for_all_ports(hub);
return 0;
}
@@ -1290,6 +1300,8 @@ static int hub_post_reset(struct usb_interface *intf)
{
struct usb_hub *hub = usb_get_intfdata(intf);
+ hub->in_reset = 0;
+ hub_pm_barrier_for_all_ports(hub);
hub_activate(hub, HUB_POST_RESET);
return 0;
}
diff --git a/drivers/usb/core/hub.h b/drivers/usb/core/hub.h
index 33bcb2c6f90a..f9b521e60128 100644
--- a/drivers/usb/core/hub.h
+++ b/drivers/usb/core/hub.h
@@ -66,6 +66,7 @@ struct usb_hub {
unsigned limited_power:1;
unsigned quiescing:1;
unsigned disconnected:1;
+ unsigned in_reset:1;
unsigned quirk_check_port_auto_suspend:1;
diff --git a/drivers/usb/core/port.c b/drivers/usb/core/port.c
index 51542f852393..37647e080599 100644
--- a/drivers/usb/core/port.c
+++ b/drivers/usb/core/port.c
@@ -81,6 +81,10 @@ static int usb_port_runtime_resume(struct device *dev)
if (!hub)
return -EINVAL;
+ if (hub->in_reset) {
+ port_dev->power_is_on = 1;
+ return 0;
+ }
usb_autopm_get_interface(intf);
set_bit(port1, hub->busy_bits);
@@ -117,6 +121,8 @@ static int usb_port_runtime_suspend(struct device *dev)
if (!hub)
return -EINVAL;
+ if (hub->in_reset)
+ return -EBUSY;
if (dev_pm_qos_flags(&port_dev->dev, PM_QOS_FLAG_NO_POWER_OFF)
== PM_QOS_FLAGS_ALL)
--
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