Re: [PATCH] USB: serial: option: add support for Quectel RM500Q in QDL mode

[Johan Hovold <johan@kernel.org>]

On Thu, Jan 16, 2020 at 11:35:42PM +0100, Reinhard Speyerer wrote:
> On Thu, Jan 16, 2020 at 05:00:16PM +0100, Johan Hovold wrote:
> > On Tue, Jan 14, 2020 at 02:29:23PM +0100, Reinhard Speyerer wrote:
> > > Add support for Quectel RM500Q in QDL mode.
> > > 
> > > T:  Bus=02 Lev=01 Prnt=01 Port=00 Cnt=01 Dev#= 24 Spd=480  MxCh= 0
> > > D:  Ver= 2.10 Cls=00(>ifc ) Sub=00 Prot=00 MxPS=64 #Cfgs=  1
> > > P:  Vendor=2c7c ProdID=0800 Rev= 0.00
> > > S:  Manufacturer=Qualcomm CDMA Technologies MSM
> > > S:  Product=QUSB_BULK_SN:xxxxxxxx
> > > S:  SerialNumber=xxxxxxxx
> > > C:* #Ifs= 1 Cfg#= 1 Atr=a0 MxPwr=  2mA
> > > I:* If#= 0 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=ff Prot=10 Driver=option
> > > E:  Ad=81(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
> > > E:  Ad=01(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
> > > 
> > > It is assumed that the ZLP flag required for other Qualcomm-based
> > > 5G devices also applies to Quectel RM500Q.
> > > 
> > > Signed-off-by: Reinhard Speyerer <rspmn@arcor.de>
> > > ---
> > > diff --git a/drivers/usb/serial/option.c b/drivers/usb/serial/option.c
> > > index 62bad1b2c18e..084cc2fff3ae 100644
> > > --- a/drivers/usb/serial/option.c
> > > +++ b/drivers/usb/serial/option.c
> > > @@ -1107,6 +1107,8 @@ static const struct usb_device_id option_ids[] = {
> > >  	{ USB_DEVICE_AND_INTERFACE_INFO(QUECTEL_VENDOR_ID, QUECTEL_PRODUCT_EM12, 0xff, 0, 0) },
> > >  	{ USB_DEVICE_AND_INTERFACE_INFO(QUECTEL_VENDOR_ID, QUECTEL_PRODUCT_RM500Q, 0xff, 0xff, 0x30) },
> > >  	{ USB_DEVICE_AND_INTERFACE_INFO(QUECTEL_VENDOR_ID, QUECTEL_PRODUCT_RM500Q, 0xff, 0, 0) },
> > > +	{ USB_DEVICE_AND_INTERFACE_INFO(QUECTEL_VENDOR_ID, QUECTEL_PRODUCT_RM500Q, 0xff, 0xff, 0x10),
> > > +	  .driver_info = ZLP },
> > 
> > By the way, don't you want NCTRL(0) here too (cf. Telit SBL FN980).
> 
> Hi Johan,
> 
> NCTRL(0) is also used for the diag port of the Telit FN980 while it
> is not used for the diag port of the RM500Q in Kristian's patch.

But that's not necessarily the same firmware implementation running for
diag and QDL, right?
 
> So far I have not observed any problems when using the diag and the QDL
> ports of the RM500Q without NCTRL(0).
> 
> Unless you or Kristian would prefer to have this changed I would suggest
> to keep it as is now.

Fair enough. We can always add that later if someone confirms it isn't
needed or even incorrect (we should probably at least add a debug
statement for the return value of that control request).

Johan