Merge branch 'r8152-reg-garbage'

Douglas Anderson says:

====================
r8152: Avoid writing garbage to the adapter's registers

This series is the result of a cooperative debug effort between
Realtek and the ChromeOS team. On ChromeOS, we've noticed that Realtek
Ethernet adapters can sometimes get so wedged that even a reboot of
the host can't get them to enumerate again, assuming that the adapter
was on a powered hub and din't lose power when the host rebooted. This
is sometimes seen in the ChromeOS automated testing lab. The only way
to recover adapters in this state is to manually power cycle them.

I managed to reproduce one instance of this wedging (unknown if this
is truly related to what the test lab sees) by doing this:
1. Start a flood ping from a host to the device.
2. Drop the device into kdb.
3. Wait 90 seconds.
4. Resume from kdb (the "g" command).
5. Wait another 45 seconds.

Upon analysis, Realtek realized this was happening:

1. The Linux driver was getting a "Tx timeout" after resuming from kdb
   and then trying to reset itself.
2. As part of the reset, the Linux driver was attempting to do a
   read-modify-write of the adapter's registers.
3. The read would fail (due to a timeout) and the driver pretended
   that the register contained all 0xFFs. See commit f53a7ad18959
   ("r8152: Set memory to all 0xFFs on failed reg reads")
4. The driver would take this value of all 0xFFs, modify it, and
   attempt to write it back to the adapter.
5. By this time the USB channel seemed to recover and thus we'd
   successfully write a value that was mostly 0xFFs to the adpater.
6. The adapter didn't like this and would wedge itself.

Another Engineer also managed to reproduce wedging of the Realtek
Ethernet adpater during a reboot test on an AMD Chromebook. In that
case he was sometimes seeing -EPIPE returned from the control
transfers.

This patch series fixes both issues.

Changes in v5:
- ("Run the unload routine if we have errors during probe") new for v5.
- ("Cancel hw_phy_work if we have an error in probe") new for v5.
- ("Release firmware if we have an error in probe") new for v5.
- Removed extra mutex_unlock() left over in v4.
- Fixed minor typos.
- Don't do queue an unbind/bind reset if probe fails; just retry probe.

Changes in v4:
- Took out some unnecessary locks/unlocks of the control mutex.
- Added comment about reading version causing probe fail if 3 fails.
- Added text to commit msg about the potential unbind/bind loop.

Changes in v3:
- Fixed v2 changelog ending up in the commit message.
- farmework -> framework in comments.

Changes in v2:
- ("Check for unplug in rtl_phy_patch_request()") new for v2.
- ("Check for unplug in r8153b_ups_en() / r8153c_ups_en()") new for v2.
- ("Rename RTL8152_UNPLUG to RTL8152_INACCESSIBLE") new for v2.
- Reset patch no longer based on retry patch, since that was dropped.
- Reset patch should be robust even if failures happen in probe.
- Switched booleans to bits in the "flags" variable.
- Check for -ENODEV instead of "udev->state == USB_STATE_NOTATTACHED"
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 230 insertions, 73 deletions

diff --git a/drivers/net/usb/r8152.c b/drivers/net/usb/r8152.c
index 0c13d9950cd8..afb20c0ed688 100644
--- a/drivers/net/usb/r8152.c
+++ b/drivers/net/usb/r8152.c
@@ -764,7 +764,7 @@ enum rtl_register_content {
 
 /* rtl8152 flags */
 enum rtl8152_flags {
-	RTL8152_UNPLUG = 0,
+	RTL8152_INACCESSIBLE = 0,
 	RTL8152_SET_RX_MODE,
 	WORK_ENABLE,
 	RTL8152_LINK_CHG,
@@ -773,6 +773,9 @@ enum rtl8152_flags {
 	SCHEDULE_TASKLET,
 	GREEN_ETHERNET,
 	RX_EPROTO,
+	IN_PRE_RESET,
+	PROBED_WITH_NO_ERRORS,
+	PROBE_SHOULD_RETRY,
 };
 
 #define DEVICE_ID_LENOVO_USB_C_TRAVEL_HUB		0x721e
@@ -953,6 +956,8 @@ struct r8152 {
 	u8 version;
 	u8 duplex;
 	u8 autoneg;
+
+	unsigned int reg_access_reset_count;
 };
 
 /**
@@ -1200,6 +1205,96 @@ static unsigned int agg_buf_sz = 16384;
 
 #define RTL_LIMITED_TSO_SIZE	(size_to_mtu(agg_buf_sz) - sizeof(struct tx_desc))
 
+/* If register access fails then we block access and issue a reset. If this
+ * happens too many times in a row without a successful access then we stop
+ * trying to reset and just leave access blocked.
+ */
+#define REGISTER_ACCESS_MAX_RESETS	3
+
+static void rtl_set_inaccessible(struct r8152 *tp)
+{
+	set_bit(RTL8152_INACCESSIBLE, &tp->flags);
+	smp_mb__after_atomic();
+}
+
+static void rtl_set_accessible(struct r8152 *tp)
+{
+	clear_bit(RTL8152_INACCESSIBLE, &tp->flags);
+	smp_mb__after_atomic();
+}
+
+static
+int r8152_control_msg(struct r8152 *tp, unsigned int pipe, __u8 request,
+		      __u8 requesttype, __u16 value, __u16 index, void *data,
+		      __u16 size, const char *msg_tag)
+{
+	struct usb_device *udev = tp->udev;
+	int ret;
+
+	if (test_bit(RTL8152_INACCESSIBLE, &tp->flags))
+		return -ENODEV;
+
+	ret = usb_control_msg(udev, pipe, request, requesttype,
+			      value, index, data, size,
+			      USB_CTRL_GET_TIMEOUT);
+
+	/* No need to issue a reset to report an error if the USB device got
+	 * unplugged; just return immediately.
+	 */
+	if (ret == -ENODEV)
+		return ret;
+
+	/* If the write was successful then we're done */
+	if (ret >= 0) {
+		tp->reg_access_reset_count = 0;
+		return ret;
+	}
+
+	dev_err(&udev->dev,
+		"Failed to %s %d bytes at %#06x/%#06x (%d)\n",
+		msg_tag, size, value, index, ret);
+
+	/* Block all future register access until we reset. Much of the code
+	 * in the driver doesn't check for errors. Notably, many parts of the
+	 * driver do a read/modify/write of a register value without
+	 * confirming that the read succeeded. Writing back modified garbage
+	 * like this can fully wedge the adapter, requiring a power cycle.
+	 */
+	rtl_set_inaccessible(tp);
+
+	/* If probe hasn't yet finished, then we'll request a retry of the
+	 * whole probe routine if we get any control transfer errors. We
+	 * never have to clear this bit since we free/reallocate the whole "tp"
+	 * structure if we retry probe.
+	 */
+	if (!test_bit(PROBED_WITH_NO_ERRORS, &tp->flags)) {
+		set_bit(PROBE_SHOULD_RETRY, &tp->flags);
+		return ret;
+	}
+
+	/* Failing to access registers in pre-reset is not surprising since we
+	 * wouldn't be resetting if things were behaving normally. The register
+	 * access we do in pre-reset isn't truly mandatory--we're just reusing
+	 * the disable() function and trying to be nice by powering the
+	 * adapter down before resetting it. Thus, if we're in pre-reset,
+	 * we'll return right away and not try to queue up yet another reset.
+	 * We know the post-reset is already coming.
+	 */
+	if (test_bit(IN_PRE_RESET, &tp->flags))
+		return ret;
+
+	if (tp->reg_access_reset_count < REGISTER_ACCESS_MAX_RESETS) {
+		usb_queue_reset_device(tp->intf);
+		tp->reg_access_reset_count++;
+	} else if (tp->reg_access_reset_count == REGISTER_ACCESS_MAX_RESETS) {
+		dev_err(&udev->dev,
+			"Tried to reset %d times; giving up.\n",
+			REGISTER_ACCESS_MAX_RESETS);
+	}
+
+	return ret;
+}
+
 static
 int get_registers(struct r8152 *tp, u16 value, u16 index, u16 size, void *data)
 {
@@ -1210,9 +1305,10 @@ int get_registers(struct r8152 *tp, u16 value, u16 index, u16 size, void *data)
 	if (!tmp)
 		return -ENOMEM;
 
-	ret = usb_control_msg(tp->udev, tp->pipe_ctrl_in,
-			      RTL8152_REQ_GET_REGS, RTL8152_REQT_READ,
-			      value, index, tmp, size, 500);
+	ret = r8152_control_msg(tp, tp->pipe_ctrl_in,
+				RTL8152_REQ_GET_REGS, RTL8152_REQT_READ,
+				value, index, tmp, size, "read");
+
 	if (ret < 0)
 		memset(data, 0xff, size);
 	else
@@ -1233,9 +1329,9 @@ int set_registers(struct r8152 *tp, u16 value, u16 index, u16 size, void *data)
 	if (!tmp)
 		return -ENOMEM;
 
-	ret = usb_control_msg(tp->udev, tp->pipe_ctrl_out,
-			      RTL8152_REQ_SET_REGS, RTL8152_REQT_WRITE,
-			      value, index, tmp, size, 500);
+	ret = r8152_control_msg(tp, tp->pipe_ctrl_out,
+				RTL8152_REQ_SET_REGS, RTL8152_REQT_WRITE,
+				value, index, tmp, size, "write");
 
 	kfree(tmp);
 
@@ -1244,10 +1340,8 @@ int set_registers(struct r8152 *tp, u16 value, u16 index, u16 size, void *data)
 
 static void rtl_set_unplug(struct r8152 *tp)
 {
-	if (tp->udev->state == USB_STATE_NOTATTACHED) {
-		set_bit(RTL8152_UNPLUG, &tp->flags);
-		smp_mb__after_atomic();
-	}
+	if (tp->udev->state == USB_STATE_NOTATTACHED)
+		rtl_set_inaccessible(tp);
 }
 
 static int generic_ocp_read(struct r8152 *tp, u16 index, u16 size,
@@ -1256,7 +1350,7 @@ static int generic_ocp_read(struct r8152 *tp, u16 index, u16 size,
 	u16 limit = 64;
 	int ret = 0;
 
-	if (test_bit(RTL8152_UNPLUG, &tp->flags))
+	if (test_bit(RTL8152_INACCESSIBLE, &tp->flags))
 		return -ENODEV;
 
 	/* both size and indix must be 4 bytes align */
@@ -1300,7 +1394,7 @@ static int generic_ocp_write(struct r8152 *tp, u16 index, u16 byteen,
 	u16 byteen_start, byteen_end, byen;
 	u16 limit = 512;
 
-	if (test_bit(RTL8152_UNPLUG, &tp->flags))
+	if (test_bit(RTL8152_INACCESSIBLE, &tp->flags))
 		return -ENODEV;
 
 	/* both size and indix must be 4 bytes align */
@@ -1537,7 +1631,7 @@ static int read_mii_word(struct net_device *netdev, int phy_id, int reg)
 	struct r8152 *tp = netdev_priv(netdev);
 	int ret;
 
-	if (test_bit(RTL8152_UNPLUG, &tp->flags))
+	if (test_bit(RTL8152_INACCESSIBLE, &tp->flags))
 		return -ENODEV;
 
 	if (phy_id != R8152_PHY_ID)
@@ -1553,7 +1647,7 @@ void write_mii_word(struct net_device *netdev, int phy_id, int reg, int val)
 {
 	struct r8152 *tp = netdev_priv(netdev);
 
-	if (test_bit(RTL8152_UNPLUG, &tp->flags))
+	if (test_bit(RTL8152_INACCESSIBLE, &tp->flags))
 		return;
 
 	if (phy_id != R8152_PHY_ID)
@@ -1758,7 +1852,7 @@ static void read_bulk_callback(struct urb *urb)
 	if (!tp)
 		return;
 
-	if (test_bit(RTL8152_UNPLUG, &tp->flags))
+	if (test_bit(RTL8152_INACCESSIBLE, &tp->flags))
 		return;
 
 	if (!test_bit(WORK_ENABLE, &tp->flags))
@@ -1850,7 +1944,7 @@ static void write_bulk_callback(struct urb *urb)
 	if (!test_bit(WORK_ENABLE, &tp->flags))
 		return;
 
-	if (test_bit(RTL8152_UNPLUG, &tp->flags))
+	if (test_bit(RTL8152_INACCESSIBLE, &tp->flags))
 		return;
 
 	if (!skb_queue_empty(&tp->tx_queue))
@@ -1871,7 +1965,7 @@ static void intr_callback(struct urb *urb)
 	if (!test_bit(WORK_ENABLE, &tp->flags))
 		return;
 
-	if (test_bit(RTL8152_UNPLUG, &tp->flags))
+	if (test_bit(RTL8152_INACCESSIBLE, &tp->flags))
 		return;
 
 	switch (status) {
@@ -2615,7 +2709,7 @@ static void bottom_half(struct tasklet_struct *t)
 {
 	struct r8152 *tp = from_tasklet(tp, t, tx_tl);
 
-	if (test_bit(RTL8152_UNPLUG, &tp->flags))
+	if (test_bit(RTL8152_INACCESSIBLE, &tp->flags))
 		return;
 
 	if (!test_bit(WORK_ENABLE, &tp->flags))
@@ -2658,7 +2752,7 @@ int r8152_submit_rx(struct r8152 *tp, struct rx_agg *agg, gfp_t mem_flags)
 	int ret;
 
 	/* The rx would be stopped, so skip submitting */
-	if (test_bit(RTL8152_UNPLUG, &tp->flags) ||
+	if (test_bit(RTL8152_INACCESSIBLE, &tp->flags) ||
 	    !test_bit(WORK_ENABLE, &tp->flags) || !netif_carrier_ok(tp->netdev))
 		return 0;
 
@@ -3058,7 +3152,7 @@ static int rtl_enable(struct r8152 *tp)
 
 static int rtl8152_enable(struct r8152 *tp)
 {
-	if (test_bit(RTL8152_UNPLUG, &tp->flags))
+	if (test_bit(RTL8152_INACCESSIBLE, &tp->flags))
 		return -ENODEV;
 
 	set_tx_qlen(tp);
@@ -3145,7 +3239,7 @@ static int rtl8153_enable(struct r8152 *tp)
 {
 	u32 ocp_data;
 
-	if (test_bit(RTL8152_UNPLUG, &tp->flags))
+	if (test_bit(RTL8152_INACCESSIBLE, &tp->flags))
 		return -ENODEV;
 
 	set_tx_qlen(tp);
@@ -3177,7 +3271,7 @@ static void rtl_disable(struct r8152 *tp)
 	u32 ocp_data;
 	int i;
 
-	if (test_bit(RTL8152_UNPLUG, &tp->flags)) {
+	if (test_bit(RTL8152_INACCESSIBLE, &tp->flags)) {
 		rtl_drop_queued_tx(tp);
 		return;
 	}
@@ -3631,7 +3725,7 @@ static u16 r8153_phy_status(struct r8152 *tp, u16 desired)
 		}
 
 		msleep(20);
-		if (test_bit(RTL8152_UNPLUG, &tp->flags))
+		if (test_bit(RTL8152_INACCESSIBLE, &tp->flags))
 			break;
 	}
 
@@ -3663,6 +3757,8 @@ static void r8153b_ups_en(struct r8152 *tp, bool enable)
 			int i;
 
 			for (i = 0; i < 500; i++) {
+				if (test_bit(RTL8152_INACCESSIBLE, &tp->flags))
+					return;
 				if (ocp_read_word(tp, MCU_TYPE_PLA, PLA_BOOT_CTRL) &
 				    AUTOLOAD_DONE)
 					break;
@@ -3703,6 +3799,8 @@ static void r8153c_ups_en(struct r8152 *tp, bool enable)
 			int i;
 
 			for (i = 0; i < 500; i++) {
+				if (test_bit(RTL8152_INACCESSIBLE, &tp->flags))
+					return;
 				if (ocp_read_word(tp, MCU_TYPE_PLA, PLA_BOOT_CTRL) &
 				    AUTOLOAD_DONE)
 					break;
@@ -4046,6 +4144,9 @@ static int rtl_phy_patch_request(struct r8152 *tp, bool request, bool wait)
 	for (i = 0; wait && i < 5000; i++) {
 		u32 ocp_data;
 
+		if (test_bit(RTL8152_INACCESSIBLE, &tp->flags))
+			return -ENODEV;
+
 		usleep_range(1000, 2000);
 		ocp_data = ocp_reg_read(tp, OCP_PHY_PATCH_STAT);
 		if ((ocp_data & PATCH_READY) ^ check)
@@ -6002,7 +6103,7 @@ static int rtl8156_enable(struct r8152 *tp)
 	u32 ocp_data;
 	u16 speed;
 
-	if (test_bit(RTL8152_UNPLUG, &tp->flags))
+	if (test_bit(RTL8152_INACCESSIBLE, &tp->flags))
 		return -ENODEV;
 
 	r8156_fc_parameter(tp);
@@ -6060,7 +6161,7 @@ static int rtl8156b_enable(struct r8152 *tp)
 	u32 ocp_data;
 	u16 speed;
 
-	if (test_bit(RTL8152_UNPLUG, &tp->flags))
+	if (test_bit(RTL8152_INACCESSIBLE, &tp->flags))
 		return -ENODEV;
 
 	set_tx_qlen(tp);
@@ -6246,7 +6347,7 @@ out:
 
 static void rtl8152_up(struct r8152 *tp)
 {
-	if (test_bit(RTL8152_UNPLUG, &tp->flags))
+	if (test_bit(RTL8152_INACCESSIBLE, &tp->flags))
 		return;
 
 	r8152_aldps_en(tp, false);
@@ -6256,7 +6357,7 @@ static void rtl8152_up(struct r8152 *tp)
 
 static void rtl8152_down(struct r8152 *tp)
 {
-	if (test_bit(RTL8152_UNPLUG, &tp->flags)) {
+	if (test_bit(RTL8152_INACCESSIBLE, &tp->flags)) {
 		rtl_drop_queued_tx(tp);
 		return;
 	}
@@ -6271,7 +6372,7 @@ static void rtl8153_up(struct r8152 *tp)
 {
 	u32 ocp_data;
 
-	if (test_bit(RTL8152_UNPLUG, &tp->flags))
+	if (test_bit(RTL8152_INACCESSIBLE, &tp->flags))
 		return;
 
 	r8153_u1u2en(tp, false);
@@ -6311,7 +6412,7 @@ static void rtl8153_down(struct r8152 *tp)
 {
 	u32 ocp_data;
 
-	if (test_bit(RTL8152_UNPLUG, &tp->flags)) {
+	if (test_bit(RTL8152_INACCESSIBLE, &tp->flags)) {
 		rtl_drop_queued_tx(tp);
 		return;
 	}
@@ -6332,7 +6433,7 @@ static void rtl8153b_up(struct r8152 *tp)
 {
 	u32 ocp_data;
 
-	if (test_bit(RTL8152_UNPLUG, &tp->flags))
+	if (test_bit(RTL8152_INACCESSIBLE, &tp->flags))
 		return;
 
 	r8153b_u1u2en(tp, false);
@@ -6356,7 +6457,7 @@ static void rtl8153b_down(struct r8152 *tp)
 {
 	u32 ocp_data;
 
-	if (test_bit(RTL8152_UNPLUG, &tp->flags)) {
+	if (test_bit(RTL8152_INACCESSIBLE, &tp->flags)) {
 		rtl_drop_queued_tx(tp);
 		return;
 	}
@@ -6393,7 +6494,7 @@ static void rtl8153c_up(struct r8152 *tp)
 {
 	u32 ocp_data;
 
-	if (test_bit(RTL8152_UNPLUG, &tp->flags))
+	if (test_bit(RTL8152_INACCESSIBLE, &tp->flags))
 		return;
 
 	r8153b_u1u2en(tp, false);
@@ -6474,7 +6575,7 @@ static void rtl8156_up(struct r8152 *tp)
 {
 	u32 ocp_data;
 
-	if (test_bit(RTL8152_UNPLUG, &tp->flags))
+	if (test_bit(RTL8152_INACCESSIBLE, &tp->flags))
 		return;
 
 	r8153b_u1u2en(tp, false);
@@ -6547,7 +6648,7 @@ static void rtl8156_down(struct r8152 *tp)
 {
 	u32 ocp_data;
 
-	if (test_bit(RTL8152_UNPLUG, &tp->flags)) {
+	if (test_bit(RTL8152_INACCESSIBLE, &tp->flags)) {
 		rtl_drop_queued_tx(tp);
 		return;
 	}
@@ -6685,7 +6786,7 @@ static void rtl_work_func_t(struct work_struct *work)
 	/* If the device is unplugged or !netif_running(), the workqueue
 	 * doesn't need to wake the device, and could return directly.
 	 */
-	if (test_bit(RTL8152_UNPLUG, &tp->flags) || !netif_running(tp->netdev))
+	if (test_bit(RTL8152_INACCESSIBLE, &tp->flags) || !netif_running(tp->netdev))
 		return;
 
 	if (usb_autopm_get_interface(tp->intf) < 0)
@@ -6724,7 +6825,7 @@ static void rtl_hw_phy_work_func_t(struct work_struct *work)
 {
 	struct r8152 *tp = container_of(work, struct r8152, hw_phy_work.work);
 
-	if (test_bit(RTL8152_UNPLUG, &tp->flags))
+	if (test_bit(RTL8152_INACCESSIBLE, &tp->flags))
 		return;
 
 	if (usb_autopm_get_interface(tp->intf) < 0)
@@ -6851,7 +6952,7 @@ static int rtl8152_close(struct net_device *netdev)
 	netif_stop_queue(netdev);
 
 	res = usb_autopm_get_interface(tp->intf);
-	if (res < 0 || test_bit(RTL8152_UNPLUG, &tp->flags)) {
+	if (res < 0 || test_bit(RTL8152_INACCESSIBLE, &tp->flags)) {
 		rtl_drop_queued_tx(tp);
 		rtl_stop_rx(tp);
 	} else {
@@ -6884,7 +6985,7 @@ static void r8152b_init(struct r8152 *tp)
 	u32 ocp_data;
 	u16 data;
 
-	if (test_bit(RTL8152_UNPLUG, &tp->flags))
+	if (test_bit(RTL8152_INACCESSIBLE, &tp->flags))
 		return;
 
 	data = r8152_mdio_read(tp, MII_BMCR);
@@ -6928,7 +7029,7 @@ static void r8153_init(struct r8152 *tp)
 	u16 data;
 	int i;
 
-	if (test_bit(RTL8152_UNPLUG, &tp->flags))
+	if (test_bit(RTL8152_INACCESSIBLE, &tp->flags))
 		return;
 
 	r8153_u1u2en(tp, false);
@@ -6939,7 +7040,7 @@ static void r8153_init(struct r8152 *tp)
 			break;
 
 		msleep(20);
-		if (test_bit(RTL8152_UNPLUG, &tp->flags))
+		if (test_bit(RTL8152_INACCESSIBLE, &tp->flags))
 			break;
 	}
 
@@ -7068,7 +7169,7 @@ static void r8153b_init(struct r8152 *tp)
 	u16 data;
 	int i;
 
-	if (test_bit(RTL8152_UNPLUG, &tp->flags))
+	if (test_bit(RTL8152_INACCESSIBLE, &tp->flags))
 		return;
 
 	r8153b_u1u2en(tp, false);
@@ -7079,7 +7180,7 @@ static void r8153b_init(struct r8152 *tp)
 			break;
 
 		msleep(20);
-		if (test_bit(RTL8152_UNPLUG, &tp->flags))
+		if (test_bit(RTL8152_INACCESSIBLE, &tp->flags))
 			break;
 	}
 
@@ -7150,7 +7251,7 @@ static void r8153c_init(struct r8152 *tp)
 	u16 data;
 	int i;
 
-	if (test_bit(RTL8152_UNPLUG, &tp->flags))
+	if (test_bit(RTL8152_INACCESSIBLE, &tp->flags))
 		return;
 
 	r8153b_u1u2en(tp, false);
@@ -7170,7 +7271,7 @@ static void r8153c_init(struct r8152 *tp)
 			break;
 
 		msleep(20);
-		if (test_bit(RTL8152_UNPLUG, &tp->flags))
+		if (test_bit(RTL8152_INACCESSIBLE, &tp->flags))
 			return;
 	}
 
@@ -7999,7 +8100,7 @@ static void r8156_init(struct r8152 *tp)
 	u16 data;
 	int i;
 
-	if (test_bit(RTL8152_UNPLUG, &tp->flags))
+	if (test_bit(RTL8152_INACCESSIBLE, &tp->flags))
 		return;
 
 	ocp_data = ocp_read_byte(tp, MCU_TYPE_USB, USB_ECM_OP);
@@ -8020,7 +8121,7 @@ static void r8156_init(struct r8152 *tp)
 			break;
 
 		msleep(20);
-		if (test_bit(RTL8152_UNPLUG, &tp->flags))
+		if (test_bit(RTL8152_INACCESSIBLE, &tp->flags))
 			return;
 	}
 
@@ -8095,7 +8196,7 @@ static void r8156b_init(struct r8152 *tp)
 	u16 data;
 	int i;
 
-	if (test_bit(RTL8152_UNPLUG, &tp->flags))
+	if (test_bit(RTL8152_INACCESSIBLE, &tp->flags))
 		return;
 
 	ocp_data = ocp_read_byte(tp, MCU_TYPE_USB, USB_ECM_OP);
@@ -8129,7 +8230,7 @@ static void r8156b_init(struct r8152 *tp)
 			break;
 
 		msleep(20);
-		if (test_bit(RTL8152_UNPLUG, &tp->flags))
+		if (test_bit(RTL8152_INACCESSIBLE, &tp->flags))
 			return;
 	}
 
@@ -8255,7 +8356,7 @@ static int rtl8152_pre_reset(struct usb_interface *intf)
 	struct r8152 *tp = usb_get_intfdata(intf);
 	struct net_device *netdev;
 
-	if (!tp)
+	if (!tp || !test_bit(PROBED_WITH_NO_ERRORS, &tp->flags))
 		return 0;
 
 	netdev = tp->netdev;
@@ -8270,7 +8371,9 @@ static int rtl8152_pre_reset(struct usb_interface *intf)
 	napi_disable(&tp->napi);
 	if (netif_carrier_ok(netdev)) {
 		mutex_lock(&tp->control);
+		set_bit(IN_PRE_RESET, &tp->flags);
 		tp->rtl_ops.disable(tp);
+		clear_bit(IN_PRE_RESET, &tp->flags);
 		mutex_unlock(&tp->control);
 	}
 
@@ -8283,9 +8386,11 @@ static int rtl8152_post_reset(struct usb_interface *intf)
 	struct net_device *netdev;
 	struct sockaddr sa;
 
-	if (!tp)
+	if (!tp || !test_bit(PROBED_WITH_NO_ERRORS, &tp->flags))
 		return 0;
 
+	rtl_set_accessible(tp);
+
 	/* reset the MAC address in case of policy change */
 	if (determine_ethernet_addr(tp, &sa) >= 0) {
 		rtnl_lock();
@@ -9158,7 +9263,7 @@ static int rtl8152_ioctl(struct net_device *netdev, struct ifreq *rq, int cmd)
 	struct mii_ioctl_data *data = if_mii(rq);
 	int res;
 
-	if (test_bit(RTL8152_UNPLUG, &tp->flags))
+	if (test_bit(RTL8152_INACCESSIBLE, &tp->flags))
 		return -ENODEV;
 
 	res = usb_autopm_get_interface(tp->intf);
@@ -9260,7 +9365,7 @@ static const struct net_device_ops rtl8152_netdev_ops = {
 
 static void rtl8152_unload(struct r8152 *tp)
 {
-	if (test_bit(RTL8152_UNPLUG, &tp->flags))
+	if (test_bit(RTL8152_INACCESSIBLE, &tp->flags))
 		return;
 
 	if (tp->version != RTL_VER_01)
@@ -9269,7 +9374,7 @@ static void rtl8152_unload(struct r8152 *tp)
 
 static void rtl8153_unload(struct r8152 *tp)
 {
-	if (test_bit(RTL8152_UNPLUG, &tp->flags))
+	if (test_bit(RTL8152_INACCESSIBLE, &tp->flags))
 		return;
 
 	r8153_power_cut_en(tp, false);
@@ -9277,7 +9382,7 @@ static void rtl8153_unload(struct r8152 *tp)
 
 static void rtl8153b_unload(struct r8152 *tp)
 {
-	if (test_bit(RTL8152_UNPLUG, &tp->flags))
+	if (test_bit(RTL8152_INACCESSIBLE, &tp->flags))
 		return;
 
 	r8153b_power_cut_en(tp, false);
@@ -9487,16 +9592,29 @@ static u8 __rtl_get_hw_ver(struct usb_device *udev)
 	__le32 *tmp;
 	u8 version;
 	int ret;
+	int i;
 
 	tmp = kmalloc(sizeof(*tmp), GFP_KERNEL);
 	if (!tmp)
 		return 0;
 
-	ret = usb_control_msg(udev, usb_rcvctrlpipe(udev, 0),
-			      RTL8152_REQ_GET_REGS, RTL8152_REQT_READ,
-			      PLA_TCR0, MCU_TYPE_PLA, tmp, sizeof(*tmp), 500);
-	if (ret > 0)
-		ocp_data = (__le32_to_cpu(*tmp) >> 16) & VERSION_MASK;
+	/* Retry up to 3 times in case there is a transitory error. We do this
+	 * since retrying a read of the version is always safe and this
+	 * function doesn't take advantage of r8152_control_msg().
+	 */
+	for (i = 0; i < 3; i++) {
+		ret = usb_control_msg(udev, usb_rcvctrlpipe(udev, 0),
+				      RTL8152_REQ_GET_REGS, RTL8152_REQT_READ,
+				      PLA_TCR0, MCU_TYPE_PLA, tmp, sizeof(*tmp),
+				      USB_CTRL_GET_TIMEOUT);
+		if (ret > 0) {
+			ocp_data = (__le32_to_cpu(*tmp) >> 16) & VERSION_MASK;
+			break;
+		}
+	}
+
+	if (i != 0 && ret > 0)
+		dev_warn(&udev->dev, "Needed %d retries to read version\n", i);
 
 	kfree(tmp);
 
@@ -9595,25 +9713,14 @@ static bool rtl8152_supports_lenovo_macpassthru(struct usb_device *udev)
 	return 0;
 }
 
-static int rtl8152_probe(struct usb_interface *intf,
-			 const struct usb_device_id *id)
+static int rtl8152_probe_once(struct usb_interface *intf,
+			      const struct usb_device_id *id, u8 version)
 {
 	struct usb_device *udev = interface_to_usbdev(intf);
 	struct r8152 *tp;
 	struct net_device *netdev;
-	u8 version;
 	int ret;
 
-	if (intf->cur_altsetting->desc.bInterfaceClass != USB_CLASS_VENDOR_SPEC)
-		return -ENODEV;
-
-	if (!rtl_check_vendor_ok(intf))
-		return -ENODEV;
-
-	version = rtl8152_get_version(intf);
-	if (version == RTL_VER_UNKNOWN)
-		return -ENODEV;
-
 	usb_reset_device(udev);
 	netdev = alloc_etherdev(sizeof(struct r8152));
 	if (!netdev) {
@@ -9776,18 +9883,68 @@ static int rtl8152_probe(struct usb_interface *intf,
 	else
 		device_set_wakeup_enable(&udev->dev, false);
 
+	/* If we saw a control transfer error while probing then we may
+	 * want to try probe() again. Consider this an error.
+	 */
+	if (test_bit(PROBE_SHOULD_RETRY, &tp->flags))
+		goto out2;
+
+	set_bit(PROBED_WITH_NO_ERRORS, &tp->flags);
 	netif_info(tp, probe, netdev, "%s\n", DRIVER_VERSION);
 
 	return 0;
 
+out2:
+	unregister_netdev(netdev);
+
 out1:
 	tasklet_kill(&tp->tx_tl);
+	cancel_delayed_work_sync(&tp->hw_phy_work);
+	if (tp->rtl_ops.unload)
+		tp->rtl_ops.unload(tp);
+	rtl8152_release_firmware(tp);
 	usb_set_intfdata(intf, NULL);
 out:
+	if (test_bit(PROBE_SHOULD_RETRY, &tp->flags))
+		ret = -EAGAIN;
+
 	free_netdev(netdev);
 	return ret;
 }
 
+#define RTL8152_PROBE_TRIES	3
+
+static int rtl8152_probe(struct usb_interface *intf,
+			 const struct usb_device_id *id)
+{
+	u8 version;
+	int ret;
+	int i;
+
+	if (intf->cur_altsetting->desc.bInterfaceClass != USB_CLASS_VENDOR_SPEC)
+		return -ENODEV;
+
+	if (!rtl_check_vendor_ok(intf))
+		return -ENODEV;
+
+	version = rtl8152_get_version(intf);
+	if (version == RTL_VER_UNKNOWN)
+		return -ENODEV;
+
+	for (i = 0; i < RTL8152_PROBE_TRIES; i++) {
+		ret = rtl8152_probe_once(intf, id, version);
+		if (ret != -EAGAIN)
+			break;
+	}
+	if (ret == -EAGAIN) {
+		dev_err(&intf->dev,
+			"r8152 failed probe after %d tries; giving up\n", i);
+		return -ENODEV;
+	}
+
+	return ret;
+}
+
 static void rtl8152_disconnect(struct usb_interface *intf)
 {
 	struct r8152 *tp = usb_get_intfdata(intf);