Re: [PATCH v2] USB: serial: qcserial: Support for SDX55 based Sierra Wireless 5G modules

On Thu, Jul 01, 2021 at 06:41:26PM +0200, Stefan Brüns wrote:

On Donnerstag, 24. Juni 2021 09:28:59 CEST Johan Hovold wrote:

quoted

[ +CC: Daniele and Bjørn ]

On Fri, Jun 11, 2021 at 03:58:41PM +0200, Stefan Brüns wrote:

quoted

The devices exposes two different interface compositions:
- QDL mode, single interface
- MBIM mode, MBIM class compliant plus AT/DM(/ADB)

Current firmware versions (up to 01.07.19) do not expose an NMEA port.

We already have at least one SDX55 based modem (FN980) supported by the
option driver. Any particular reason why you chose to add it to qcserial
instead of option?

Support for qualcomm based modems are spread over option and qcserial. All 
other Sierra devices are supported by qcserial.

Ok, but we may still end up adding this one to option if matching on the
interface protocol works.

quoted

Note that the FN980 also needs the ZLP flag set in QDL (flashing) mode,
I'd assume this one needs it too.

It depends if you implement the Firehose protocol in accordance to the 
specification or not. 80-NG319-1 (Firehose specification) explicitly states to 
pad any XML command packet which is an exact multiple of 512 bytes with an 
extra newline or other whitespace character.

Thanks for the details. If you're referring to the device-side
implementation it seems a bit fragile to not just set the ZLP flag since
apparently there are some non-standard implementations out there. But
sure, we can do that later if needed.

Johan