Pre-Condition
At the time of reset resume of a USB device, both self and bus powered
devices might go to a low power state or power off state depending on
the acceptable suspend time power of the system.
In case the device experiences a power glitch or completely powers off
during suspend-resume, the device will lose its internal state and
hence it'll again need a set interface from class driver on reset resume
operation.
Issue
So far our experiments were based on a USB gadget working on cdc_eem
protocol.
We have seen that device is unable to continue the packet transfer on
bulk endpoints after the reset resume operation.
Solution
We have added a .reset_resume function for cdc_eem protocol which sends a
set interface command on the Control endpoint. And calls the existing
usbnet_resume thereafter
Signed-off-by: Vikas Bansal <vikas.bansal@xxxxxxxxxxx>
Signed-off-by: Sumit Batra <sumit.batra@xxxxxxxxxxx>
diff --git a/drivers/net/usb/cdc_eem.c b/drivers/net/usb/cdc_eem.c
index f7180f8..1f6f7ea 100644
--- a/drivers/net/usb/cdc_eem.c
+++ b/drivers/net/usb/cdc_eem.c
@@ -342,6 +342,19 @@ next:
return 1;
}
+static int cdc_eem_resume(struct usb_interface *intf)
+{
+ int ret = 0;
+ struct usbnet *dev = usb_get_intfdata(intf);
+
+ ret = usbnet_get_endpoints(dev, intf);
+ if (ret < 0)
+ goto err;
+ ret = usbnet_resume(intf);
+err:
+ return ret;
+}
+
static const struct driver_info eem_info = {
.description = "CDC EEM Device",
.flags = FLAG_ETHER | FLAG_POINTTOPOINT,
@@ -371,6 +384,7 @@ static struct usb_driver eem_driver = {
.disconnect = usbnet_disconnect,
.suspend = usbnet_suspend,
.resume = usbnet_resume,
+ .reset_resume = cdc_eem_resume,
.disable_hub_initiated_lpm = 1,
};
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