Commit 1e8bbe6c authored by Bjørn Mork's avatar Bjørn Mork Committed by David S. Miller
Browse files

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



commit bd329e12 ("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: default avatarGeir Haatveit <nospam@haatveit.nu>
Reported-by: default avatarTommi Kyntola <kynde@ts.ray.fi>
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=54791


Signed-off-by: default avatarBjørn Mork <bjorn@mork.no>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent a5b8db91

drivers/net/usb/cdc_mbim.c

+1 −10
Original line number Diff line number Diff line
@@ -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;

drivers/net/usb/cdc_ncm.c

+32 −17
Original line number Diff line number Diff line
@@ -55,6 +55,14 @@ 


#define	DRIVER_VERSION				"14-Mar-2012"



#if IS_ENABLED(CONFIG_USB_NET_CDC_MBIM)

static bool prefer_mbim = true;

#else

static bool prefer_mbim;

#endif

module_param(prefer_mbim, bool, S_IRUGO | S_IWUSR);

MODULE_PARM_DESC(prefer_mbim, "Prefer MBIM setting on dual NCM/MBIM functions");



static void cdc_ncm_txpath_bh(unsigned long param);

static void cdc_ncm_tx_timeout_start(struct cdc_ncm_ctx *ctx);

static enum hrtimer_restart cdc_ncm_tx_timer_cb(struct hrtimer *hr_timer);
@@ -550,9 +558,12 @@ void cdc_ncm_unbind(struct usbnet *dev, struct usb_interface *intf) 
}

EXPORT_SYMBOL_GPL(cdc_ncm_unbind);



static int cdc_ncm_bind(struct usbnet *dev, struct usb_interface *intf)

/* Select the MBIM altsetting iff it is preferred and available,

 * returning the number of the corresponding data interface altsetting

 */

u8 cdc_ncm_select_altsetting(struct usbnet *dev, struct usb_interface *intf)

{

	int ret;

	struct usb_host_interface *alt;



	/* The MBIM spec defines a NCM compatible default altsetting,

	 * which we may have matched:
@@ -568,23 +579,27 @@ static int cdc_ncm_bind(struct usbnet *dev, struct usb_interface *intf) 
	 *   endpoint descriptors, shall be constructed according to

	 *   the rules given in section 6 (USB Device Model) of this

	 *   specification."

	 *

	 * Do not bind to such interfaces, allowing cdc_mbim to handle

	 * them

	 */

#if IS_ENABLED(CONFIG_USB_NET_CDC_MBIM)

	if ((intf->num_altsetting == 2) &&

	if (prefer_mbim && intf->num_altsetting == 2) {

		alt = usb_altnum_to_altsetting(intf, CDC_NCM_COMM_ALTSETTING_MBIM);

		if (alt && cdc_ncm_comm_intf_is_mbim(alt) &&

		    !usb_set_interface(dev->udev,

				       intf->cur_altsetting->desc.bInterfaceNumber,

			       CDC_NCM_COMM_ALTSETTING_MBIM)) {

				       CDC_NCM_COMM_ALTSETTING_MBIM))

			return CDC_NCM_DATA_ALTSETTING_MBIM;

	}

	return CDC_NCM_DATA_ALTSETTING_NCM;

}

EXPORT_SYMBOL_GPL(cdc_ncm_select_altsetting);



static int cdc_ncm_bind(struct usbnet *dev, struct usb_interface *intf)

{

	int ret;



	/* MBIM backwards compatible function? */

	cdc_ncm_select_altsetting(dev, intf);

	if (cdc_ncm_comm_intf_is_mbim(intf->cur_altsetting))

		return -ENODEV;

		else

			usb_set_interface(dev->udev,

					  intf->cur_altsetting->desc.bInterfaceNumber,

					  CDC_NCM_COMM_ALTSETTING_NCM);

	}

#endif



	/* NCM data altsetting is always 1 */

	ret = cdc_ncm_bind_common(dev, intf, 1);

include/linux/usb/cdc_ncm.h

+1 −0
Original line number Diff line number Diff line
@@ -127,6 +127,7 @@ struct cdc_ncm_ctx { 
	u16 connected;

};



extern u8 cdc_ncm_select_altsetting(struct usbnet *dev, struct usb_interface *intf);

extern int cdc_ncm_bind_common(struct usbnet *dev, struct usb_interface *intf, u8 data_altsetting);

extern void cdc_ncm_unbind(struct usbnet *dev, struct usb_interface *intf);

extern struct sk_buff *cdc_ncm_fill_tx_frame(struct cdc_ncm_ctx *ctx, struct sk_buff *skb, __le32 sign);

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