diff options
Diffstat (limited to 'recipes-kernel/linux')
| -rw-r--r-- | recipes-kernel/linux/linux-at91-5.4.199/linux-5.4-usb-qmi-wwan-prevent-babble.patch | 70 | ||||
| -rw-r--r-- | recipes-kernel/linux/linux-at91_5.4.199.bb | 1 |
2 files changed, 71 insertions, 0 deletions
diff --git a/recipes-kernel/linux/linux-at91-5.4.199/linux-5.4-usb-qmi-wwan-prevent-babble.patch b/recipes-kernel/linux/linux-at91-5.4.199/linux-5.4-usb-qmi-wwan-prevent-babble.patch new file mode 100644 index 0000000..0d24f81 --- /dev/null +++ b/recipes-kernel/linux/linux-at91-5.4.199/linux-5.4-usb-qmi-wwan-prevent-babble.patch @@ -0,0 +1,70 @@ +From: "Seija K." <doremylover123@gmail.com> +Date: Tue, 13 Dec 2022 12:40:52 -0500 +Subject: [PATCH] net: Fix for packets being rejected in the xHCI controller's + ring buffer + +When a packet larger than MTU arrives in Linux from the modem, it is +discarded with -EOVERFLOW error (Babble error). + +This is seen on USB3.0 and USB2.0 buses. + +This is because the MRU (Max Receive Size) is not a separate entity +from the MTU (Max Transmit Size), and the received packets can be +larger than those transmitted. + +Following the babble error, there was an endless supply of zero-length +URBs that were rejected with -EPROTO (increasing the rx input error +counter each time). + +This is only seen on USB3.0. These continue to come ad infinitum until +the modem is shut down. + +There appears to be a bug in the core USB handling code in Linux that +doesn't deal with network MTUs smaller than 1500 bytes well. + +By default, the dev->hard_mtu (the real MTU) is in lockstep with +dev->rx_urb_size (essentially an MRU), and the latter is causing +trouble. + +This has nothing to do with the modems; the issue can be reproduced by +getting a USB-Ethernet dongle, setting the MTU to 1430, and pinging +with size greater than 1406. + +Signed-off-by: Seija Kijin <doremylover123@gmail.com> + +Co-Authored-By: TarAldarion <gildeap@tcd.ie> + +Upstream-Status: Inappropriate [other] + Workaround for the babble issue, breaks qmap link aggregation that uses + datagram sizes bigger than 1504. qmap link aggregation requires datagram + sizes of 4096, 16384 bytes and so on, depending on the radio. + mPower and mLinux do not use qmap link aggregation, but set the MTU based + on the value reported by the radio (provider-specific). This patch sets + "almost-MRU" to a high and fixed value, and should be enough for our needs. + See GP-2221 for details. + +--- + drivers/net/usb/qmi_wwan.c | 7 +++++++ + 1 file changed, 7 insertions(+) + +diff --git a/drivers/net/usb/qmi_wwan.c b/drivers/net/usb/qmi_wwan.c +index 554d4e2a84a4..39db53a74b5a 100644 +--- a/drivers/net/usb/qmi_wwan.c ++++ b/drivers/net/usb/qmi_wwan.c +@@ -842,6 +842,13 @@ static int qmi_wwan_bind(struct usbnet *dev, struct usb_interface *intf) + } + dev->net->netdev_ops = &qmi_wwan_netdev_ops; + dev->net->sysfs_groups[0] = &qmi_wwan_sysfs_attr_group; ++ /* LTE Networks don't always respect their own MTU on the receiving side; ++ * e.g. AT&T pushes 1430 MTU but still allows 1500 byte packets from ++ * far-end networks. Make the receive buffer large enough to accommodate ++ * them, and add four bytes so MTU does not equal MRU on network ++ * with 1500 MTU. Otherwise, usbnet_change_mtu() will change both. ++ */ ++ dev->rx_urb_size = ETH_DATA_LEN + 4; + err: + return status; + } +-- +2.38.2 + diff --git a/recipes-kernel/linux/linux-at91_5.4.199.bb b/recipes-kernel/linux/linux-at91_5.4.199.bb index bcd58bb..64ab072 100644 --- a/recipes-kernel/linux/linux-at91_5.4.199.bb +++ b/recipes-kernel/linux/linux-at91_5.4.199.bb @@ -54,6 +54,7 @@ COMMON_PATCHES = " \ file://linux-5.4-revert-net-macb-Properly-handle-phylink-on-at91rm9200.patch \ file://linux-5.4-bring-back-PAE-bit-and-fix-NCFGR-values-applicable-f.patch \ file://linux-5.4-quiet-overlay.patch \ + file://linux-5.4-usb-qmi-wwan-prevent-babble.patch \ file://mt-at91.h \ " |