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Subject: Re: [PATCH 5.10 491/663] USB: serial: option: update interface
 mapping for ZTE P685M
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        linux-kernel@vger.kernel.org
Cc:     stable@vger.kernel.org, Johan Hovold <johan@kernel.org>,
        =?UTF-8?Q?Bj=c3=b8rn_Mork?= <bjorn@mork.no>
References: <20210301161141.760350206@linuxfoundation.org>
 <20210301161206.139213430@linuxfoundation.org>
From:   Lech Perczak <lech.perczak@gmail.com>
Message-ID: <07edca19-417d-4dab-adeb-cae7b2b17708@gmail.com>
Date:   Thu, 4 Mar 2021 00:58:19 +0100
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Hi,

On 2021-03-01 at 17:12, Greg Kroah-Hartman wrote:
> From: Lech Perczak <lech.perczak@gmail.com>
>
> commit 6420a569504e212d618d4a4736e2c59ed80a8478 upstream.
>
> This patch prepares for qmi_wwan driver support for the device.
> Previously "option" driver mapped itself to interfaces 0 and 3 (matching
> ff/ff/ff), while interface 3 is in fact a QMI port.
> Interfaces 1 and 2 (matching ff/00/00) expose AT commands,
> and weren't supported previously at all.
> Without this patch, a possible conflict would exist if device ID was
> added to qmi_wwan driver for interface 3.
>
> Update and simplify device ID to match interfaces 0-2 directly,
> to expose QCDM (0), PCUI (1), and modem (2) ports and avoid conflict
> with QMI (3), and ADB (4).
>
> The modem is used inside ZTE MF283+ router and carriers identify it as
> such.
> Interface mapping is:
> 0: QCDM, 1: AT (PCUI), 2: AT (Modem), 3: QMI, 4: ADB
>
> T:  Bus=02 Lev=02 Prnt=02 Port=05 Cnt=01 Dev#=  3 Spd=480  MxCh= 0
> D:  Ver= 2.01 Cls=00(>ifc ) Sub=00 Prot=00 MxPS=64 #Cfgs=  1
> P:  Vendor=19d2 ProdID=1275 Rev=f0.00
> S:  Manufacturer=ZTE,Incorporated
> S:  Product=ZTE Technologies MSM
> S:  SerialNumber=P685M510ZTED0000CP&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&0
> C:* #Ifs= 5 Cfg#= 1 Atr=a0 MxPwr=500mA
> I:* If#= 0 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=ff Prot=ff Driver=option
> E:  Ad=81(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
> E:  Ad=01(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
> I:* If#= 1 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=00 Prot=00 Driver=option
> E:  Ad=83(I) Atr=03(Int.) MxPS=  10 Ivl=32ms
> E:  Ad=82(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
> E:  Ad=02(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
> I:* If#= 2 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=00 Prot=00 Driver=option
> E:  Ad=85(I) Atr=03(Int.) MxPS=  10 Ivl=32ms
> E:  Ad=84(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
> E:  Ad=03(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
> I:* If#= 3 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=ff Prot=ff Driver=qmi_wwan
> E:  Ad=87(I) Atr=03(Int.) MxPS=   8 Ivl=32ms
> E:  Ad=86(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
> E:  Ad=04(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
> I:* If#= 4 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=42 Prot=01 Driver=(none)
> E:  Ad=88(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
> E:  Ad=05(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
>
> Cc: Johan Hovold <johan@kernel.org>
> Cc: Bjørn Mork <bjorn@mork.no>
> Signed-off-by: Lech Perczak <lech.perczak@gmail.com>
> Link: https://lore.kernel.org/r/20210207005443.12936-1-lech.perczak@gmail.com
> Cc: stable@vger.kernel.org
> Signed-off-by: Johan Hovold <johan@kernel.org>
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> ---
>   drivers/usb/serial/option.c |    3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
>
> --- a/drivers/usb/serial/option.c
> +++ b/drivers/usb/serial/option.c
> @@ -1569,7 +1569,8 @@ static const struct usb_device_id option
>   	{ USB_DEVICE_AND_INTERFACE_INFO(ZTE_VENDOR_ID, 0x1272, 0xff, 0xff, 0xff) },
>   	{ USB_DEVICE_AND_INTERFACE_INFO(ZTE_VENDOR_ID, 0x1273, 0xff, 0xff, 0xff) },
>   	{ USB_DEVICE_AND_INTERFACE_INFO(ZTE_VENDOR_ID, 0x1274, 0xff, 0xff, 0xff) },
> -	{ USB_DEVICE_AND_INTERFACE_INFO(ZTE_VENDOR_ID, 0x1275, 0xff, 0xff, 0xff) },
> +	{ USB_DEVICE(ZTE_VENDOR_ID, 0x1275),	/* ZTE P685M */
> +	  .driver_info = RSVD(3) | RSVD(4) },
>   	{ USB_DEVICE_AND_INTERFACE_INFO(ZTE_VENDOR_ID, 0x1276, 0xff, 0xff, 0xff) },
>   	{ USB_DEVICE_AND_INTERFACE_INFO(ZTE_VENDOR_ID, 0x1277, 0xff, 0xff, 0xff) },
>   	{ USB_DEVICE_AND_INTERFACE_INFO(ZTE_VENDOR_ID, 0x1278, 0xff, 0xff, 0xff) },
>
>
If this patch is selected, then 88eee9b7b42e69fb622ddb3ff6f37e8e4347f5b2 
("net: usb: qmi_wwan: support ZTE P685M modem")
probably should be selected, too. This patch frees up an interface to be 
claimed by qmi_wwan driver by the mentioned patch.
The mentioned patch only adds a device ID to qmi_wwan driver.

In my opinion, those two should come in pair. Regarding version, I think 
that backporting to 5.4.y and later is enough, as OpenWrt,
from which those patches originate is currently on 5.4.y on the target 
requiring it, and will move to 5.10.y soon.
Backporting this would certainly make OpenWrt folks happy, however I 
don't insist on it.

-- 
With kind regards,
Lech Perczak