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From:   =?utf-8?Q?Bj=C3=B8rn_Mork?= <bjorn@mork.no>
To:     Stefan x Nilsson <stefan.x.nilsson@axis.com>
Cc:     "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>, <netdev@vger.kernel.org>,
        <linux-usb@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <kernel@axis.com>
Subject: Re: [PATCH net-next] qmi_wwan: Add rawip module param
Organization: m
References: <20230912-qmiraw-v1-1-21bc812fa0cf@axis.com>
Date:   Tue, 12 Sep 2023 09:22:20 +0200
In-Reply-To: <20230912-qmiraw-v1-1-21bc812fa0cf@axis.com> (Stefan x. Nilsson's
        message of "Tue, 12 Sep 2023 09:04:13 +0200")
Message-ID: <87a5tramab.fsf@miraculix.mork.no>
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Stefan x Nilsson <stefan.x.nilsson@axis.com> writes:

> Certain QMI modems will start communicating in rawip mode after
> bootup, and will not work properly if communication starts off in
> ethernet mode. So add a module parameter, rawip_as_default, that
> can be used to load the qmi driver in rawip mode.
>
> The advantage compared to changing rawip at a later point using
> sysfs is that the os will not detect the device and start talking
> to it while the driver is still in incorrect mode.
>
> Signed-off-by: Stefan x Nilsson <stefan.x.nilsson@axis.com>
> ---
>  drivers/net/usb/qmi_wwan.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)
>
> diff --git a/drivers/net/usb/qmi_wwan.c b/drivers/net/usb/qmi_wwan.c
> index 344af3c5c836..968c60ececf8 100644
> --- a/drivers/net/usb/qmi_wwan.c
> +++ b/drivers/net/usb/qmi_wwan.c
> @@ -46,6 +46,10 @@
>   * commands on a serial interface
>   */
>=20=20
> +/* Module parameters */
> +static bool rawip_as_default;
> +module_param(rawip_as_default, bool, 0644);
> +
>  /* driver specific data */
>  struct qmi_wwan_state {
>  	struct usb_driver *subdriver;
> @@ -843,6 +847,13 @@ static int qmi_wwan_bind(struct usbnet *dev, struct =
usb_interface *intf)
>  	}
>  	dev->net->netdev_ops =3D &qmi_wwan_netdev_ops;
>  	dev->net->sysfs_groups[0] =3D &qmi_wwan_sysfs_attr_group;
> +
> +	/* Set the driver into rawip mode if requested by module param */
> +	if (rawip_as_default) {
> +		info->flags |=3D QMI_WWAN_FLAG_RAWIP;
> +		qmi_wwan_netdev_setup(dev->net);
> +	}
> +
>  err:
>  	return status;
>  }
>

NAK

There is no reason to start communicating with the device before
changing the framing, using the existing sysfs interface.

This seems to be a workaround for some userspace bug.  I don't think we
yet another userspace knob for that.  And certainly not one that applies
to every device.


Bj=C3=B8rn