[PATCH] usbnet: add reset_resume quirk to prevent resume failure

[PATCH] usbnet: add reset_resume quirk to prevent resume failure

[Vivek Kumar Bhagat]

Ideally, usbnet_resume is sufficient for device resume operation.
since usbcore function usb_resume_device() sets udev->reset_resume
flag as a quirk solution, reset_resume() quirk we can keep in
class driver also. We checked on dongle DA-Queen UFE20C,
without reset function resume operation fails. Reason could be
some power glitch during suspend time due to which device lose
its internal state and it needs a device phy reset again during
resume to recover.

Signed-off-by: Vivek Kumar Bhagat <vivek.bhagat@samsung.com>
Signed-off-by: Vikas Bansal <vikas.bansal@samsung.com>
Signed-off-by: Sangmin Bae <sm79.bae@samsung.com>
---
 drivers/net/usb/asix_devices.c |    1 +
 drivers/net/usb/cdc_eem.c      |    1 +
 drivers/net/usb/usbnet.c       |   17 +++++++++++++++++
 include/linux/usb/usbnet.h     |    1 +
 4 files changed, 20 insertions(+)

diff --git a/drivers/net/usb/asix_devices.c b/drivers/net/usb/asix_devices.c
index 5cabefc..68dda61 100644
--- a/drivers/net/usb/asix_devices.c
+++ b/drivers/net/usb/asix_devices.c
@@ -1097,6 +1097,7 @@ static struct usb_driver asix_driver = {
 	.probe =	usbnet_probe,
 	.suspend =	usbnet_suspend,
 	.resume =	usbnet_resume,
+	.reset_resume = usbnet_reset_resume,
 	.disconnect =	usbnet_disconnect,
 	.supports_autosuspend = 1,
 	.disable_hub_initiated_lpm = 1,
diff --git a/drivers/net/usb/cdc_eem.c b/drivers/net/usb/cdc_eem.c
index f7180f8..83b6857 100644
--- a/drivers/net/usb/cdc_eem.c
+++ b/drivers/net/usb/cdc_eem.c
@@ -371,6 +371,7 @@ static struct usb_driver eem_driver = {
 	.disconnect =	usbnet_disconnect,
 	.suspend =	usbnet_suspend,
 	.resume =	usbnet_resume,
+	.reset_resume = usbnet_reset_resume,
 	.disable_hub_initiated_lpm = 1,
 };
 
diff --git a/drivers/net/usb/usbnet.c b/drivers/net/usb/usbnet.c
index 61ba464..f56c176 100644
--- a/drivers/net/usb/usbnet.c
+++ b/drivers/net/usb/usbnet.c
@@ -1876,6 +1876,23 @@ int usbnet_resume (struct usb_interface *intf)
 }
 EXPORT_SYMBOL_GPL(usbnet_resume);
 
+int usbnet_reset_resume(struct usb_interface *intf)
+{
+	struct usbnet *dev = usb_get_intfdata(intf);
+	int ret;
+
+	if (dev->driver_info->reset) {
+		ret = dev->driver_info->reset(dev);
+		if (ret < 0)
+			return ret;
+
+		return usbnet_resume(intf);
+	}
+
+	return -EINVAL;
+}
+EXPORT_SYMBOL_GPL(usbnet_reset_resume);
+
 /*
  * Either a subdriver implements manage_power, then it is assumed to always
  * be ready to be suspended or it reports the readiness to be suspended
diff --git a/include/linux/usb/usbnet.h b/include/linux/usb/usbnet.h
index 6e0ce8c..0b261d5 100644
--- a/include/linux/usb/usbnet.h
+++ b/include/linux/usb/usbnet.h
@@ -177,6 +177,7 @@ struct driver_info {
 extern int usbnet_probe(struct usb_interface *, const struct usb_device_id *);
 extern int usbnet_suspend(struct usb_interface *, pm_message_t);
 extern int usbnet_resume(struct usb_interface *);
+extern int usbnet_reset_resume(struct usb_interface *);
 extern void usbnet_disconnect(struct usb_interface *);
 extern void usbnet_device_suggests_idle(struct usbnet *dev);
 
-- 
1.7.9.5

Re: [PATCH] usbnet: add reset_resume quirk to prevent resume failure

[David Miller]

From: Vivek Kumar Bhagat <vivek.bhagat@samsung.com>
Date: Thu, 30 Jun 2016 10:41:59 +0000 (GMT)

> 
> Ideally, usbnet_resume is sufficient for device resume operation.
> since usbcore function usb_resume_device() sets udev->reset_resume
> flag as a quirk solution, reset_resume() quirk we can keep in
> class driver also. We checked on dongle DA-Queen UFE20C,
> without reset function resume operation fails. Reason could be
> some power glitch during suspend time due to which device lose
> its internal state and it needs a device phy reset again during
> resume to recover.
> 
> Signed-off-by: Vivek Kumar Bhagat <vivek.bhagat@samsung.com>
> Signed-off-by: Vikas Bansal <vikas.bansal@samsung.com>
> Signed-off-by: Sangmin Bae <sm79.bae@samsung.com>

You've seen this necessary for one device, yet you are doing this
new reset for all usbnet devices.

That doesn't sound correct or safe at all.

I'm not applying this, sorry.