[PATCH v2] r8152: disable RX aggregation on Dell TB16 dock

[Kai-Heng Feng]

r8153 on Dell TB15/16 dock corrupts rx packets.

This change is suggested by Realtek. They guess that the XHCI controller
doesn't have enough buffer, and their guesswork is correct, once the RX
aggregation gets disabled, the issue is gone.

ASMedia is currently working on a real sulotion for this issue.

Dell and ODM confirm the bcdDevice and iSerialNumber is unique for TB16.

Note that TB15 has different bcdDevice and iSerialNumber, which are not
unique values. If you still have TB15, please contact Dell to replace it
with TB16.

BugLink: https://bugs.launchpad.net/bugs/1729674
Cc: Mario Limonciello <mario.limonciello@xxxxxxxx>
Signed-off-by: Kai-Heng Feng <kai.heng.feng@xxxxxxxxxxxxx>
---
v2:
- Disable RX aggregation instead of disable RX checksum
- Use bcdDevice and iSerialNumber to uniquely identify Dell TB16

 drivers/net/usb/r8152.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/drivers/net/usb/r8152.c b/drivers/net/usb/r8152.c
index d51d9abf7986..0657203ffb91 100644
--- a/drivers/net/usb/r8152.c
+++ b/drivers/net/usb/r8152.c
@@ -606,6 +606,7 @@ enum rtl8152_flags {
 	PHY_RESET,
 	SCHEDULE_NAPI,
 	GREEN_ETHERNET,
+	DELL_TB_RX_AGG_BUG,
 };
 
 /* Define these values to match your device */
@@ -1798,6 +1799,9 @@ static int r8152_tx_agg_fill(struct r8152 *tp, struct tx_agg *agg)
 		dev_kfree_skb_any(skb);
 
 		remain = agg_buf_sz - (int)(tx_agg_align(tx_data) - agg->head);
+
+		if (test_bit(DELL_TB_RX_AGG_BUG, &tp->flags))
+			break;
 	}
 
 	if (!skb_queue_empty(&skb_head)) {
@@ -4133,6 +4137,9 @@ static void r8153_init(struct r8152 *tp)
 	/* rx aggregation */
 	ocp_data = ocp_read_word(tp, MCU_TYPE_USB, USB_USB_CTRL);
 	ocp_data &= ~(RX_AGG_DISABLE | RX_ZERO_EN);
+	if (test_bit(DELL_TB_RX_AGG_BUG, &tp->flags))
+		ocp_data |= RX_AGG_DISABLE;
+
 	ocp_write_word(tp, MCU_TYPE_USB, USB_USB_CTRL, ocp_data);
 
 	rtl_tally_reset(tp);
@@ -5207,6 +5214,12 @@ static int rtl8152_probe(struct usb_interface *intf,
 		netdev->hw_features &= ~NETIF_F_RXCSUM;
 	}
 
+	if (le16_to_cpu(udev->descriptor.bcdDevice) == 0x3011 &&
+	    udev->serial && !strcmp(udev->serial, "000001000000")) {
+		dev_info(&udev->dev, "Dell TB16 Dock, disable RX aggregation");
+		set_bit(DELL_TB_RX_AGG_BUG, &tp->flags);
+	}
+
 	netdev->ethtool_ops = &ops;
 	netif_set_gso_max_size(netdev, RTL_LIMITED_TSO_SIZE);
 
-- 
2.15.1