| Message ID | 1363259113-6909-1-git-send-email-bjorn@mork.no |
|---|---|
| State | Accepted, archived |
| Delegated to: | David Miller |
| Headers | show |
On Thu, 2013-03-14 at 12:05 +0100, Bjørn Mork wrote: > 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> > --- > > We now have two users independently reporting this as a 3.8 regression, > so something needs to be done. I am not sure if adding a new module > parameter is acceptable for stable, but this problem is definitely a > regression and no other solutions came up in response to my RFC. > > The only real alternative I see for stable, is disabling MBIM support > on any dual NCM/MBIM function. Which of course will be a regression > for any user wanting MBIM, making it unacceptable. [...] It definitely makes sense for this to be a run-time parameter. And the default seems correct for custom kernels. For a distribution kernel - at least for Debian, where we can't assume kernel and userland are always updated together - I think the compile-time default should be false, and the userland package (presumably ModemManager?) can install a modprobe.conf file to override that once it can handle MBIM. We handled KMS transitions in a similar way. I don't know that it's worth having a Kconfig option for that, though. Ben.
Ben Hutchings <ben@decadent.org.uk> writes: > On Thu, 2013-03-14 at 12:05 +0100, Bjørn Mork wrote: >> 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> >> --- >> >> We now have two users independently reporting this as a 3.8 regression, >> so something needs to be done. I am not sure if adding a new module >> parameter is acceptable for stable, but this problem is definitely a >> regression and no other solutions came up in response to my RFC. >> >> The only real alternative I see for stable, is disabling MBIM support >> on any dual NCM/MBIM function. Which of course will be a regression >> for any user wanting MBIM, making it unacceptable. > [...] > > It definitely makes sense for this to be a run-time parameter. And the > default seems correct for custom kernels. > > For a distribution kernel - at least for Debian, where we can't assume > kernel and userland are always updated together - I think the > compile-time default should be false, and the userland package > (presumably ModemManager?) can install a modprobe.conf file to override > that once it can handle MBIM. We handled KMS transitions in a similar > way. I don't know that it's worth having a Kconfig option for that, > though. We could consider always defaulting to NCM. That would remove the ugliest parts of the code as well. Should I send a new version with such a change? Bundling a modprobe.conf file to enable MBIM with userland tools supporting it is a great idea, and sounds feasible for custom built systems as well. (BTW, if there is any doubt about it, I feel really bad about my recent request to enable MBIM in Debian, where I wrote "enabling the driver will not prevent any existing solution from working.". At the time, I had not seen any of these dual NCM/MBIM functions and I just didn't think about the problems such devices would run into. Sorry about that. I guess I owe you one more...) Bjørn -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Fri, 2013-03-15 at 08:02 +0100, Bjørn Mork wrote: > Ben Hutchings <ben@decadent.org.uk> writes: > > > On Thu, 2013-03-14 at 12:05 +0100, Bjørn Mork wrote: > >> 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> > >> --- > >> > >> We now have two users independently reporting this as a 3.8 regression, > >> so something needs to be done. I am not sure if adding a new module > >> parameter is acceptable for stable, but this problem is definitely a > >> regression and no other solutions came up in response to my RFC. > >> > >> The only real alternative I see for stable, is disabling MBIM support > >> on any dual NCM/MBIM function. Which of course will be a regression > >> for any user wanting MBIM, making it unacceptable. > > [...] > > > > It definitely makes sense for this to be a run-time parameter. And the > > default seems correct for custom kernels. > > > > For a distribution kernel - at least for Debian, where we can't assume > > kernel and userland are always updated together - I think the > > compile-time default should be false, and the userland package > > (presumably ModemManager?) can install a modprobe.conf file to override > > that once it can handle MBIM. We handled KMS transitions in a similar > > way. I don't know that it's worth having a Kconfig option for that, > > though. > > We could consider always defaulting to NCM. That would remove the > ugliest parts of the code as well. Should I send a new version with > such a change? We could, but I fear that would annoy people building custom kernels. > Bundling a modprobe.conf file to enable MBIM with userland tools > supporting it is a great idea, and sounds feasible for custom built > systems as well. Using unpatched Linux & ModemManager (or other userland) needs to just work. So if Linux is going to have MBIM disabled by default then upstream ModemManager needs to ship and install that modprobe.conf file. > (BTW, if there is any doubt about it, I feel really bad about my recent > request to enable MBIM in Debian, where I wrote "enabling the driver > will not prevent any existing solution from working.". At the time, I > had not seen any of these dual NCM/MBIM functions and I just didn't > think about the problems such devices would run into. Sorry about > that. I guess I owe you one more...) It's called experimental for a reason. :-) Ben.
From: Bjørn Mork <bjorn@mork.no> Date: Thu, 14 Mar 2013 12:05:13 +0100 > 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> Ok, this is fine as a solution for now, applied and queued up for -stable. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/net/usb/cdc_mbim.c b/drivers/net/usb/cdc_mbim.c index 248d2dc..16c8429 100644 --- a/drivers/net/usb/cdc_mbim.c +++ b/drivers/net/usb/cdc_mbim.c @@ -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; diff --git a/drivers/net/usb/cdc_ncm.c b/drivers/net/usb/cdc_ncm.c index 61b74a2..4709fa3 100644 --- a/drivers/net/usb/cdc_ncm.c +++ b/drivers/net/usb/cdc_ncm.c @@ -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) && - !usb_set_interface(dev->udev, - intf->cur_altsetting->desc.bInterfaceNumber, - CDC_NCM_COMM_ALTSETTING_MBIM)) { - 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); + 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)) + return CDC_NCM_DATA_ALTSETTING_MBIM; } -#endif + 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; /* NCM data altsetting is always 1 */ ret = cdc_ncm_bind_common(dev, intf, 1); diff --git a/include/linux/usb/cdc_ncm.h b/include/linux/usb/cdc_ncm.h index 3b8f9d4..cc25b70 100644 --- a/include/linux/usb/cdc_ncm.h +++ b/include/linux/usb/cdc_ncm.h @@ -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);
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> --- We now have two users independently reporting this as a 3.8 regression, so something needs to be done. I am not sure if adding a new module parameter is acceptable for stable, but this problem is definitely a regression and no other solutions came up in response to my RFC. The only real alternative I see for stable, is disabling MBIM support on any dual NCM/MBIM function. Which of course will be a regression for any user wanting MBIM, making it unacceptable. drivers/net/usb/cdc_mbim.c | 11 +--------- drivers/net/usb/cdc_ncm.c | 49 ++++++++++++++++++++++++++++--------------- include/linux/usb/cdc_ncm.h | 1 + 3 files changed, 34 insertions(+), 27 deletions(-)