Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Fri, 29 Jul 2022 08:37:21 +0200
From:   Johan Hovold <johan@kernel.org>
To:     sdlyyxy <sdlyyxy@bupt.edu.cn>
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Reinhard Speyerer <rspmn@arcor.de>, linux-usb@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] USB: usb-serial-simple: add new device id for OPPO R11
Message-ID: <YuOAIdKlJKyh9o2k@hovoldconsulting.com>
References: <20220715142444.4173681-1-gregkh@linuxfoundation.org>
 <119D7B0F-7809-464A-AFF1-DF72FFF9E63F@bupt.edu.cn>
 <YtKrbucYNulPEKUp@arcor.de>
 <YtRtswctFMLxeglu@kroah.com>
 <YtXG3EVrRKAG7WVx@arcor.de>
 <YtwjiWG5ZFBvCZ1M@hovoldconsulting.com>
 <Yt1QhCIiUf97Dl3D@kroah.com>
 <Yt1WfSZk03Plpnan@hovoldconsulting.com>
 <B47DDA3C-3CE2-4E25-B764-1744A4AA04A0@bupt.edu.cn>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <B47DDA3C-3CE2-4E25-B764-1744A4AA04A0@bupt.edu.cn>
Precedence: bulk

On Fri, Jul 29, 2022 at 02:13:56PM +0800, sdlyyxy wrote:
> 
> > On Jul 24, 2022, at 22:26, Johan Hovold <johan@kernel.org> wrote:
> > 
> > On Sun, Jul 24, 2022 at 04:00:36PM +0200, Greg Kroah-Hartman wrote:
> >> On Sat, Jul 23, 2022 at 06:36:25PM +0200, Johan Hovold wrote:
> >>> On Mon, Jul 18, 2022 at 10:47:24PM +0200, Reinhard Speyerer wrote:
> > 
> >>>> Please don't give the OPPO R11 diag port on Linux a bad name by letting
> >>>> the usb-serial-simple driver handle it.
> >>> 
> >>> So while I'm not sure bandwidth is really a problem, I still tend to
> >>> agree that we should add this one to the option driver for now as that
> >>> is how we handle (non-GOBI) Qualcomm modems and their QCDM ports.
> >> 
> >> If you want it to stay on the option driver, that's fine, but I still
> >> think it feels odd as it obviously does not follow the vendor-specific
> >> protocol that the option driver supports.
> > 
> > But we've been dumping modem device-id entries in there since forever.
> > 
> > The entries added to option have been for devices whose interfaces did
> > not follow any particular pattern (e.g. unlike the old GOBI modems).
> > 
> > And as Reinhard mentioned, the line-control requests (which follow CDC)
> > are actually required by some Qualcomm modems so moving things out would
> > need to be done carefully.
> > 
> > On the other hand, that request likely isn't needed for any QCDM/DIAG
> > ports, but who knows for sure.
> 
> Test result for bandwidth problem:
> Sending 0x1f mask (diag command: 0x7d0500001f000000) and running LTE
> speedtest on the device, both option and simple can dump more than 80Mbps.
> The CRC of diag packets is OK at this high speed, so it seems that
> there is no message loss. I think this bandwidth is enough.
> 
> For the flow control problem, it seems the SetControlLineState request
> send by option (usb_wwan) has no effect on the device. Both with and
> without this request the diag port works the same.
> 
> Hope this can help you decide which driver to choose :)

Thanks a lot for confirming! I'll try to revisit this next week and get
something merged for 5.20-rcN.

Johan