diff options
| author | Ben Chan | 2014-03-19 14:00:06 -0700 |
|---|---|---|
| committer | David S. Miller | 2014-03-20 16:57:35 -0400 |
| commit | 259fef033ffe4e70bf7f358c53400a09f1b5384e (patch) | |
| tree | 2c972b7f21f84be2ea4ba8afa319ffc700f2ccf1 | |
| parent | bfe9b3f8c5229e5de4fd18e941866bc410d16334 (diff) | |
net: cdc_ncm: respect operator preferred MTU reported by MBIM
According to "Universal Serial Bus Communications Class Subclass
Specification for Mobile Broadband Interface Model, Revision 1.0,
Errata-1" published by USB-IF, the wMTU field of the MBIM extended
functional descriptor indicates the operator preferred MTU for IP data
streams.
This patch modifies cdc_ncm_setup to ensure that the MTU value set on
the usbnet device does not exceed the operator preferred MTU indicated
by wMTU if the MBIM device exposes a MBIM extended functional
descriptor.
Signed-off-by: Ben Chan <benchan@chromium.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | drivers/net/usb/cdc_ncm.c | 17 | ||||
| -rw-r--r-- | include/linux/usb/cdc_ncm.h | 1 |
2 files changed, 18 insertions, 0 deletions
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 @@ out: /* 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; |