On Mon, Sep 21, 2020 at 05:04:34PM +0200, Oliver Neukum wrote:
> Am Montag, den 21.09.2020, 16:28 +0200 schrieb Johan Hovold:
> > On Mon, Sep 21, 2020 at 04:16:56PM +0200, Oliver Neukum wrote:
> > > Am Montag, den 21.09.2020, 15:59 +0200 schrieb Johan Hovold:
> > > > For interfaces that lack a union descriptor, probe for a
> > > > "combined-interface" before falling back to the call-management
> > > > descriptor instead of the other way round.
> > >
> > > Hi,
>
> Hi,
>
> > >
> > > the more I look at this the more it seems to me like the
> > > device that has the quirk does NOT have a collapsed interface
> > > but two interfaces and just a lack of a union descriptor.
> >
> > But then why name the quirk NO_DATA_INTERFACE if it has a data
>
> In hindsight that seems not the best name.
>
> > interface? By hardcoding the data-interface number to be the one and
> > only interface, you'd end up probing for a "combined" interface also
> > with a broken call-management descriptor.
>
> Well, by the changelog assuming a combined interface caused an oops.
> Thence I am forced to conclude that the davices _has_ a separate
> data interface, but no union descriptor.
No, the oops was probably due to the missing sanity check later added by
403dff4e2c94 ("USB: cdc-acm: check for valid interfaces").
With a broken call-management descriptor pointing to a non-existent
interface we'd oops before that commit.
> > Side note: I really think we should start mandating lsusb output to go
> > along with any patch for quirky devices.
>
> Good idea. Convince Greg.
Heh. I'm sure he can be convinced. :)
Johan
