From 55f854dd5bdd8e19b936a00ef1f8d776ac32c7b0 Mon Sep 17 00:00:00 2001 From: Laurent Vivier Date: Wed, 4 Mar 2026 14:43:38 +0100 Subject: qmi_wwan: allow max_mtu above hard_mtu to control rx_urb_size Commit c7159e960f14 ("usbnet: limit max_mtu based on device's hard_mtu") capped net->max_mtu to the device's hard_mtu in usbnet_probe(). While this correctly prevents oversized packets on standard USB network devices, it breaks the qmi_wwan driver. qmi_wwan relies on userspace (e.g. ModemManager) setting a large MTU on the wwan0 interface to configure rx_urb_size via usbnet_change_mtu(). QMI modems negotiate USB transfer sizes of 16,383 or 32,767 bytes, and the USB receive buffers must be sized accordingly. With max_mtu capped to hard_mtu (~1500 bytes), userspace can no longer raise the MTU, the receive buffers remain small, and download speeds drop from >300 Mbps to ~0.8 Mbps. Introduce a FLAG_NOMAXMTU driver flag that allows individual usbnet drivers to opt out of the max_mtu cap. Set this flag in qmi_wwan's driver_info structures to restore the previous behavior for QMI devices, while keeping the safety fix in place for all other usbnet drivers. Fixes: c7159e960f14 ("usbnet: limit max_mtu based on device's hard_mtu") Cc: stable@vger.kernel.org Link: https://lore.kernel.org/lkml/CAPh3n803k8JcBPV5qEzUB-oKzWkAs-D5CU7z=Vd_nLRCr5ZqQg@mail.gmail.com/ Reported-by: Koen Vandeputte Tested-by: Daniele Palmas Signed-off-by: Laurent Vivier Link: https://patch.msgid.link/20260304134338.1785002-1-lvivier@redhat.com Signed-off-by: Jakub Kicinski --- include/linux/usb/usbnet.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux/usb') diff --git a/include/linux/usb/usbnet.h b/include/linux/usb/usbnet.h index b0e84896e6ac..bbf799ccf3b3 100644 --- a/include/linux/usb/usbnet.h +++ b/include/linux/usb/usbnet.h @@ -132,6 +132,7 @@ struct driver_info { #define FLAG_MULTI_PACKET 0x2000 #define FLAG_RX_ASSEMBLE 0x4000 /* rx packets may span >1 frames */ #define FLAG_NOARP 0x8000 /* device can't do ARP */ +#define FLAG_NOMAXMTU 0x10000 /* allow max_mtu above hard_mtu */ /* init device ... can sleep, or cause probe() failure */ int (*bind)(struct usbnet *, struct usb_interface *); -- cgit v1.2.3 From 9f6a983cfa22ac662c86e60816d3a357d4b551e9 Mon Sep 17 00:00:00 2001 From: Jie Deng Date: Fri, 27 Feb 2026 16:49:31 +0800 Subject: usb: core: new quirk to handle devices with zero configurations Some USB devices incorrectly report bNumConfigurations as 0 in their device descriptor, which causes the USB core to reject them during enumeration. logs: usb 1-2: device descriptor read/64, error -71 usb 1-2: no configurations usb 1-2: can't read configurations, error -22 However, these devices actually work correctly when treated as having a single configuration. Add a new quirk USB_QUIRK_FORCE_ONE_CONFIG to handle such devices. When this quirk is set, assume the device has 1 configuration instead of failing with -EINVAL. This quirk is applied to the device with VID:PID 5131:2007 which exhibits this behavior. Signed-off-by: Jie Deng Link: https://patch.msgid.link/20260227084931.1527461-1-dengjie03@kylinos.cn Signed-off-by: Greg Kroah-Hartman --- Documentation/admin-guide/kernel-parameters.txt | 3 +++ drivers/usb/core/config.c | 6 +++++- drivers/usb/core/quirks.c | 5 +++++ include/linux/usb/quirks.h | 3 +++ 4 files changed, 16 insertions(+), 1 deletion(-) (limited to 'include/linux/usb') diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index cb850e5290c2..7d907efe9f49 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -8183,6 +8183,9 @@ Kernel parameters p = USB_QUIRK_SHORT_SET_ADDRESS_REQ_TIMEOUT (Reduce timeout of the SET_ADDRESS request from 5000 ms to 500 ms); + q = USB_QUIRK_FORCE_ONE_CONFIG (Device + claims zero configurations, + forcing to 1); Example: quirks=0781:5580:bk,0a5c:5834:gij usbhid.mousepoll= diff --git a/drivers/usb/core/config.c b/drivers/usb/core/config.c index 1cd5fa61dc76..6a1fd967e0a6 100644 --- a/drivers/usb/core/config.c +++ b/drivers/usb/core/config.c @@ -927,7 +927,11 @@ int usb_get_configuration(struct usb_device *dev) dev->descriptor.bNumConfigurations = ncfg = USB_MAXCONFIG; } - if (ncfg < 1) { + if (ncfg < 1 && dev->quirks & USB_QUIRK_FORCE_ONE_CONFIG) { + dev_info(ddev, "Device claims zero configurations, forcing to 1\n"); + dev->descriptor.bNumConfigurations = 1; + ncfg = 1; + } else if (ncfg < 1) { dev_err(ddev, "no configurations\n"); return -EINVAL; } diff --git a/drivers/usb/core/quirks.c b/drivers/usb/core/quirks.c index e347236d83e8..7bd408db05f4 100644 --- a/drivers/usb/core/quirks.c +++ b/drivers/usb/core/quirks.c @@ -140,6 +140,8 @@ static int quirks_param_set(const char *value, const struct kernel_param *kp) case 'p': flags |= USB_QUIRK_SHORT_SET_ADDRESS_REQ_TIMEOUT; break; + case 'q': + flags |= USB_QUIRK_FORCE_ONE_CONFIG; /* Ignore unrecognized flag characters */ } } @@ -589,6 +591,9 @@ static const struct usb_device_id usb_quirk_list[] = { /* VCOM device */ { USB_DEVICE(0x4296, 0x7570), .driver_info = USB_QUIRK_CONFIG_INTF_STRINGS }, + /* Noji-MCS SmartCard Reader */ + { USB_DEVICE(0x5131, 0x2007), .driver_info = USB_QUIRK_FORCE_ONE_CONFIG }, + /* INTEL VALUE SSD */ { USB_DEVICE(0x8086, 0xf1a5), .driver_info = USB_QUIRK_RESET_RESUME }, diff --git a/include/linux/usb/quirks.h b/include/linux/usb/quirks.h index 2f7bd2fdc616..b3cc7beab4a3 100644 --- a/include/linux/usb/quirks.h +++ b/include/linux/usb/quirks.h @@ -78,4 +78,7 @@ /* skip BOS descriptor request */ #define USB_QUIRK_NO_BOS BIT(17) +/* Device claims zero configurations, forcing to 1 */ +#define USB_QUIRK_FORCE_ONE_CONFIG BIT(18) + #endif /* __LINUX_USB_QUIRKS_H */ -- cgit v1.2.3