diff --git a/drivers/net/usb/cdc_ncm.c b/drivers/net/usb/cdc_ncm.c index dbff290ed0e4..e8711a8cfa01 100644 --- a/drivers/net/usb/cdc_ncm.c +++ b/drivers/net/usb/cdc_ncm.c @@ -74,6 +74,7 @@ static int cdc_ncm_setup(struct usbnet *dev) u8 iface_no; int err; int eth_hlen; + u16 mbim_mtu; u16 ntb_fmt_supported; __le16 max_datagram_size; @@ -261,6 +262,14 @@ static int cdc_ncm_setup(struct usbnet *dev) /* set MTU to max supported by the device if necessary */ if (dev->net->mtu > ctx->max_datagram_size - eth_hlen) dev->net->mtu = ctx->max_datagram_size - eth_hlen; + + /* do not exceed operater preferred MTU */ + if (ctx->mbim_extended_desc) { + mbim_mtu = le16_to_cpu(ctx->mbim_extended_desc->wMTU); + if (mbim_mtu != 0 && mbim_mtu < dev->net->mtu) + dev->net->mtu = mbim_mtu; + } + return 0; } @@ -399,6 +408,14 @@ int cdc_ncm_bind_common(struct usbnet *dev, struct usb_interface *intf, u8 data_ ctx->mbim_desc = (const struct usb_cdc_mbim_desc *)buf; break; + case USB_CDC_MBIM_EXTENDED_TYPE: + if (buf[0] < sizeof(*(ctx->mbim_extended_desc))) + break; + + ctx->mbim_extended_desc = + (const struct usb_cdc_mbim_extended_desc *)buf; + break; + default: break; } diff --git a/include/linux/usb/cdc_ncm.h b/include/linux/usb/cdc_ncm.h index c3fa80745996..bdf05fb36729 100644 --- a/include/linux/usb/cdc_ncm.h +++ b/include/linux/usb/cdc_ncm.h @@ -93,6 +93,7 @@ struct cdc_ncm_ctx { const struct usb_cdc_ncm_desc *func_desc; const struct usb_cdc_mbim_desc *mbim_desc; + const struct usb_cdc_mbim_extended_desc *mbim_extended_desc; const struct usb_cdc_ether_desc *ether_desc; struct usb_interface *control; diff --git a/include/uapi/linux/usb/cdc.h b/include/uapi/linux/usb/cdc.h index f35aa0a338c7..b6a9cdd6e096 100644 --- a/include/uapi/linux/usb/cdc.h +++ b/include/uapi/linux/usb/cdc.h @@ -56,6 +56,7 @@ #define USB_CDC_OBEX_TYPE 0x15 #define USB_CDC_NCM_TYPE 0x1a #define USB_CDC_MBIM_TYPE 0x1b +#define USB_CDC_MBIM_EXTENDED_TYPE 0x1c /* "Header Functional Descriptor" from CDC spec 5.2.3.1 */ struct usb_cdc_header_desc { @@ -205,6 +206,17 @@ struct usb_cdc_mbim_desc { __u8 bmNetworkCapabilities; } __attribute__ ((packed)); +/* "MBIM Extended Functional Descriptor" from CDC MBIM spec 1.0 errata-1 */ +struct usb_cdc_mbim_extended_desc { + __u8 bLength; + __u8 bDescriptorType; + __u8 bDescriptorSubType; + + __le16 bcdMBIMExtendedVersion; + __u8 bMaxOutstandingCommandMessages; + __le16 wMTU; +} __attribute__ ((packed)); + /*-------------------------------------------------------------------------*/ /*