Changes in v2:
- Modified logic for executing the runtime PM resume. Using a sychronous get
call to avoid race conditions.
During the following scenario, the DWC3 runtime suspend routine is blocked as
the connected flag is still true:
1. Enumerate device w/ host.
2. Gadget is unbinded
- echo "" > /sys/kernel/config/usb_gadget/g1/UDC
3. Disconnect the USB cable (VBUS low)
4. No dwc3_gadget_disconnect_interrupt() seen (since controller is
halted from step#1)
5. Runtime PM autosuspend fails due to "dwc->connected" being true
(cleared in dwc3_gadget_disconnect_interrupt())
6. Gadget binded
- echo udc_name > /sys/kernel/config/usb_gadget/g1/UDC
7. No runtime suspend until cable is plugged in and out
Technically, for device initiated disconnects, there is no active session/link
with the host, so the DWC3 controller should be allowed to go into a low power
state. Also, we need to now consider when re-binding the UDC,
dwc3_gadget_set_speed() is executed before dwc3_gadget_pullup(), so if the DWC3
controller is suspended/disabled, while accessing the DCFG, that could result in
bus timeouts, etc... Change the dwc3_gadget_set_speed() to save the speed
being requested, and program it during dwc3_gadget_run_stop(), which is executed
during PM runtime resume. If not, previous setting will be overridden as we
execute a DWC3 controller reset during PM runtime resume.
Wesley Cheng (2):
usb: dwc3: gadget: Allow runtime suspend if UDC unbinded
usb: dwc3: gadget: Preserve UDC max speed setting
drivers/usb/dwc3/core.h | 1 +
drivers/usb/dwc3/gadget.c | 121 ++++++++++++++++++++++----------------
2 files changed, 71 insertions(+), 51 deletions(-)
--
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project
The DWC3 runtime suspend routine checks for the USB connected parameter to
determine if the controller can enter into a low power state. The
connected state is only set to false after receiving a disconnect event.
However, in the case of a device initiated disconnect (i.e. UDC unbind),
the controller is halted and a disconnect event is never generated. Set
the connected flag to false if issuing a device initiated disconnect to
allow the controller to be suspended.
Signed-off-by: Wesley Cheng <[email protected]>
---
drivers/usb/dwc3/gadget.c | 13 +++++++++++++
1 file changed, 13 insertions(+)
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 5d879b7606d5..babf977cadc0 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -2012,6 +2012,17 @@ static int dwc3_gadget_pullup(struct usb_gadget *g, int is_on)
}
}
+ /*
+ * Check the return value for successful resume, or error. For a
+ * successful resume, the DWC3 runtime PM resume routine will handle
+ * the run stop sequence, so avoid duplicate operations here.
+ */
+ ret = pm_runtime_get_sync(dwc->dev);
+ if (!ret || ret < 0) {
+ pm_runtime_put(dwc->dev);
+ return 0;
+ }
+
/*
* Synchronize any pending event handling before executing the controller
* halt routine.
@@ -2050,10 +2061,12 @@ static int dwc3_gadget_pullup(struct usb_gadget *g, int is_on)
dwc->ev_buf->lpos = (dwc->ev_buf->lpos + count) %
dwc->ev_buf->length;
}
+ dwc->connected = false;
}
ret = dwc3_gadget_run_stop(dwc, is_on, false);
spin_unlock_irqrestore(&dwc->lock, flags);
+ pm_runtime_put(dwc->dev);
return ret;
}
--
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project