Re: Linux MBIM
- From: Dan Williams <dcbw redhat com>
- To: Greg Suarez <gpsuarez2512 gmail com>
- Cc: NetworkManager List <networkmanager-list gnome org>
- Subject: Re: Linux MBIM
- Date: Tue, 24 Jul 2012 18:03:22 -0500
On Wed, 2012-07-18 at 16:17 -0700, Greg Suarez wrote:
>
>
> On Mon, Jul 16, 2012 at 12:28 AM, Bjørn Mork <bjorn mork no> wrote:
> Aleksander Morgado <aleksander lanedo com> writes:
>
> >> I was wondering if there's any effort going on to support
> MBIM devices
> >> on Linux?
> >>
> >
> > No plans yet for ModemManager (see thread [1]). Is there any
> device
> > out there which already supports that protocol?
> >
> > Cheers,
> >
> > [1]
> >
> https://mail.gnome.org/archives/networkmanager-list/2011-November/msg00352.html
>
>
> If I understand this correctly, MBIM devices will combine CDC
> NCM with a
> MBIM control channel in the exact same way QMI devices combine
> CDC ECM
> with a QMI control channel. That means that the driver
> support could be
> done as simple as combining cdc_ncm with the cdc_wdm subdriver
> (either
> in the existing cdc_ncm driver, or as a new separate driver
> reusing code
> from cdc_ncm).
>
> If this was done, then we would have the MBIM control channel
> exported
> to userspace as a /dev/cdc-wdmX device, exactly like qmi_wwan
> exports
> its QMI control channel. Leaving MBIM control protocol
> implementation
> for userspace make sense for the same reasons it made sense to
> leave QMI
> implementation for userspace. Boy, am I happy Marcel and
> others
> convinced me to do that :-)
>
> I was on the same line of thinking but wasn't aware of the QMI driver.
> Could you point out its location to me?
>
>
>
> Hmm, I see now "The only difference is that instead of
> transporting
> Ethernet frames, MBIM transports raw IP data streams". So we
> definitely
> need a new driver based on cdc_ncm. Exporting and reusing a
> bit of
> cdc_ncm would probably make most sense. And it might also be
> necessary
> to extend the cdc_wdm subdriver interface if the cdc_ncm
> driver need to
> see the USB_CDC_NOTIFY_NETWORK_CONNECTION and
> USB_CDC_NOTIFY_SPEED_CHANGE
> notifications, or if it needs to send any control messages
> after the
> probe phase. Don't know if it does. Doesn't really look like
> it…
>
> All this should still be a piece of cake to stitch together.
> If there
> had been any devices, that is. So, no, I don't know of any
> effort to
> support MBIM on Linux. There just isn't any need for it yet.
> The basic
> kernel driver support can be added in a few weeks if
> necessary.
>
> See also the reply from Torgny Johansson in the thread
> Aleksander refer
> to, pointing to this press release:
> http://www.ericsson.com/news/111201_ericsson_to_phase_out_pc_modules_for_mobile_broadband_access_244188808_c
>
> I am guessing here, but the whole MBIM thing looks like it was
> driven by
> Ericsson, and it might just not happen when they have put it
> on hold.
> Qualcomm are likely to be happy with their current QMI
> approach. Not
> sure what value they would see in replacing that with a new
> standardized
> protocol, if they are going to be the only ones using the new
> protocol...
> Others? Microsoft? Yes, I guess they could drive this if they
> decided
> that MBIM is the "RNDIS of wwan devices". Maybe they will??
>
> A question back to you, Greg: Why do you ask?
>
> I ask because I've been assigned to either come up with a MBIM driver
> or help with an existing effort.
Ideally the control channel and ethernet (or Raw IP) bits get done in
the kernel drivers, while for the actual control protocol we have a
simple LGPL userspace library that apps like ModemManager can make use
of to talk over that control channel. A lot like we've done for QMI,
DIAG, and WMC already. Then we can just plug that code in like we've
done for all the other methods.
Dan
>
> Do you know of any
> device? Or planned device? Where can I get one? :-)
>
> I should be getting a dev board sometime in the next few weeks. I
> don't even know the manufacturer.
> Where can you get one? no idea.
>
>
>
>
>
> Bjørn
>
> Thanks,
>
> Greg
> _______________________________________________
> networkmanager-list mailing list
> networkmanager-list gnome org
> https://mail.gnome.org/mailman/listinfo/networkmanager-list
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