qmi_wwan: Add quirk for Quectel dynamic config

commit e4bf63482c309287ca84d91770ffa7dcc18e37eb upstream.

Most, if not all, Quectel devices use dynamic interface numbers, and
users are able to change the USB configuration at will. Matching on for
example interface number is therefore not possible.

Instead, the QMI device can be identified by looking at the interface
class, subclass and protocol (all 0xff), as well as the number of
endpoints. The reason we need to look at the number of endpoints, is
that the diagnostic port interface has the same class, subclass and
protocol as QMI. However, the diagnostic port only has two endpoints,
while QMI has three.

Until now, we have identified the QMI device by combining a match on
class, subclass and protocol, with a call to the function
quectel_diag_detect(). In quectel_diag_detect(), we check if the number
of endpoints matches for known Quectel vendor/product ids.

Adding new vendor/product ids to quectel_diag_detect() is not a good
long-term solution. This commit replaces the function with a quirk, and
applies the quirk to affected Quectel devices that I have been able to
test the change with (EP06, EM12 and EC25). If the quirk is set and the
number of endpoints equal two, we return from qmi_wwan_probe() with
-ENODEV.

[In order for this patch to apply cleanly to 4.14, two minor changes had
to be made. First, the original work-around (quectel_diag_detect()) for
the dynamic interface numbers was never backported to 4.14, so there is
no need to remove this code. Second, support for the EM12 was also not
backported to 4.14. Since supporting EM12 is a trivial change (just
another VID/PID match), and the match for EM12 is changed by this patch,
I chose to not submit adding EM12-support as a separate patch.]

Signed-off-by: Kristian Evensen <kristian.evensen@gmail.com>
Acked-by: Bjørn Mork <bjorn@mork.no>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

0 files changed, 0 insertions, 0 deletions