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net: cdc_ncm, cdc_mbim: allow user to prefer NCM for backwards compatibility

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commit bd329e1 ("net: cdc_ncm: do not bind to NCM compatible MBIM devices")
introduced a new policy, preferring MBIM for dual NCM/MBIM functions if
the cdc_mbim driver was enabled.  This caused a regression for users
wanting to use NCM.

Devices implementing NCM backwards compatibility according to section
3.2 of the MBIM v1.0 specification allow either NCM or MBIM on a single
USB function, using different altsettings.  The cdc_ncm and cdc_mbim
drivers will both probe such functions, and must agree on a common
policy for selecting either MBIM or NCM.  Until now, this policy has
been set at build time based on CONFIG_USB_NET_CDC_MBIM.

Use a module parameter to set the system policy at runtime, allowing the
user to prefer NCM on systems with the cdc_mbim driver.

Cc: Greg Suarez <gsuarez@smithmicro.com>
Cc: Alexey Orishko <alexey.orishko@stericsson.com>
Reported-by: Geir Haatveit <nospam@haatveit.nu>
Reported-by: Tommi Kyntola <kynde@ts.ray.fi>
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=54791
Signed-off-by: Bjørn Mork <bjorn@mork.no>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Bjørn Mork
2013-03-14 01:05:13 +00:00
committed by David S. Miller
parent a5b8db9144
commit 1e8bbe6cd0
3 changed files with 34 additions and 27 deletions
Download Patch File Download Diff File Expand all files Collapse all files

11
drivers/net/usb/cdc_mbim.c
View File

@@ -68,18 +68,9 @@ static int cdc_mbim_bind(struct usbnet *dev, struct usb_interface *intf)
struct cdc_ncm_ctx *ctx;
struct usb_driver *subdriver = ERR_PTR(-ENODEV);
int ret = -ENODEV;
u8 data_altsetting = CDC_NCM_DATA_ALTSETTING_NCM;
u8 data_altsetting = cdc_ncm_select_altsetting(dev, intf);
struct cdc_mbim_state *info = (void *)&dev->data;
/* see if interface supports MBIM alternate setting */
if (intf->num_altsetting == 2) {
if (!cdc_ncm_comm_intf_is_mbim(intf->cur_altsetting))
usb_set_interface(dev->udev,
intf->cur_altsetting->desc.bInterfaceNumber,
CDC_NCM_COMM_ALTSETTING_MBIM);
data_altsetting = CDC_NCM_DATA_ALTSETTING_MBIM;
}
/* Probably NCM, defer for cdc_ncm_bind */
if (!cdc_ncm_comm_intf_is_mbim(intf->cur_altsetting))
goto err;