On Thu, 1 May 2014, Dan Williams wrote:
> > @@ -122,6 +127,11 @@ static int usb_port_runtime_suspend(stru
> > == PM_QOS_FLAGS_ALL)
> > return -EAGAIN;
> >
> > + if (hub->in_reset) {
> > + port_dev->power_is_on = 0;
> > + return 0;
> > + }
>
> Why lie? Just return -EBUSY and be done.
Good idea; the complete, updated patch is below. (It's against
3.15-rc2, without any of your RFC changes.)
> In fact that also has the
> nice side effect of clearing runtime errors it seems.
Not really, because if there was an earlier runtime PM error then
dev->power.runtime_error would be set, so rpm_check_suspend_allowed()
would fail and the suspend callback wouldn't get called in the first
place.
Alan Stern
8<---------------------------------------------------------------->8
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 <stern@xxxxxxxxxxxxxxxxxxx>
---
[as1745]
drivers/usb/core/hub.c | 12 ++++++++++++
drivers/usb/core/hub.h | 1 +
drivers/usb/core/port.c | 6 ++++++
3 files changed, 19 insertions(+)
Index: usb-3.15/drivers/usb/core/hub.h
===================================================================
--- usb-3.15.orig/drivers/usb/core/hub.h
+++ usb-3.15/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;
Index: usb-3.15/drivers/usb/core/hub.c
===================================================================
--- usb-3.15.orig/drivers/usb/core/hub.c
+++ usb-3.15/drivers/usb/core/hub.c
@@ -1276,12 +1276,22 @@ static void hub_quiesce(struct usb_hub *
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_int
{
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;
}
Index: usb-3.15/drivers/usb/core/port.c
===================================================================
--- usb-3.15.orig/drivers/usb/core/port.c
+++ usb-3.15/drivers/usb/core/port.c
@@ -81,6 +81,10 @@ static int usb_port_runtime_resume(struc
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(stru
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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