[1/2] usb: serial: option: Fix the lackage for Quectel EG95 LTE modem support

* Add reset-resume callback for resetting USB devices after MCU exits
from suspend/sleep mode.

* Because Quectel EG95 uses USB interface 4 as a USB network device, so
return from option_startup() to prevent being used as a USB serial
device.

Fixes: da6902e5b6db ("USB: serial: option: add Quectel EG95 LTE modem"

Signed-off-by: William Sung <william.sung@advantech.com.tw>
---
 drivers/usb/serial/option.c | 6 ++++++
 1 file changed, 6 insertions(+)

Hi William,

Il giorno mar 1 set 2020 alle ore 07:14 William Sung
<william.sung@advantech.com.tw> ha scritto:
>
> As required by the USB protocol, add zero packet support for Quectel
> EG95 LTE modem module.
>
> Fixes: f815dd5cf48b ("net: usb: qmi_wwan: add support for Quectel EG95
> LTE modem"

If I'm not wrong, that commit is just related to qmi_wwan.

>
> Signed-off-by: William Sung <william.sung@advantech.com.tw>
> ---
>  drivers/usb/serial/usb_wwan.c | 12 ++++++++++--
>  1 file changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/usb/serial/usb_wwan.c b/drivers/usb/serial/usb_wwan.c
> index 4b9845807bee..75495c939ac6 100644
> --- a/drivers/usb/serial/usb_wwan.c
> +++ b/drivers/usb/serial/usb_wwan.c
> @@ -467,6 +467,7 @@ static struct urb *usb_wwan_setup_urb(struct usb_serial_port *port,
>         struct usb_serial *serial = port->serial;
>         struct usb_wwan_intf_private *intfdata = usb_get_serial_data(serial);
>         struct urb *urb;
> +       struct usb_device_descriptor *desc = &serial->dev->descriptor;
>
>         urb = usb_alloc_urb(0, GFP_KERNEL);     /* No ISO */
>         if (!urb)
> @@ -476,8 +477,15 @@ static struct urb *usb_wwan_setup_urb(struct usb_serial_port *port,
>                           usb_sndbulkpipe(serial->dev, endpoint) | dir,
>                           buf, len, callback, ctx);
>
> -       if (intfdata->use_zlp && dir == USB_DIR_OUT)
> -               urb->transfer_flags |= URB_ZERO_PACKET;
> +       if (dir == USB_DIR_OUT) {
> +               if (intfdata->use_zlp)
> +                       urb->transfer_flags |= URB_ZERO_PACKET;
> +
> +               /* Add zero packet support for Quectel EG95 */
> +               if (desc->idVendor == cpu_to_le16(0x2C7C) &&
> +                       desc->idProduct == cpu_to_le16(0x0195))
> +                       urb->transfer_flags |= URB_ZERO_PACKET;
> +       }

Why not simply add the ZLP flag in option for that device?

Regards,
Daniele

>
>         return urb;
>  }
> --
> 2.17.1
>

On Tue, Sep 01, 2020 at 01:00:21PM +0800, William Sung wrote:
> * Add reset-resume callback for resetting USB devices after MCU exits
> from suspend/sleep mode.

Please split this in it's own patch and argue for why it's needed.

> * Because Quectel EG95 uses USB interface 4 as a USB network device, so
> return from option_startup() to prevent being used as a USB serial
> device.
>
> Fixes: da6902e5b6db ("USB: serial: option: add Quectel EG95 LTE modem"
> 
> Signed-off-by: William Sung <william.sung@advantech.com.tw>
> ---
>  drivers/usb/serial/option.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/usb/serial/option.c b/drivers/usb/serial/option.c
> index 89b3192af326..9de8aec47e5e 100644
> --- a/drivers/usb/serial/option.c
> +++ b/drivers/usb/serial/option.c
> @@ -2069,6 +2069,7 @@ static struct usb_serial_driver option_1port_device = {
>  #ifdef CONFIG_PM
>  	.suspend           = usb_wwan_suspend,
>  	.resume            = usb_wwan_resume,
> +	.reset_resume      = usb_wwan_resume,
>  #endif
>  };
>  
> @@ -2104,6 +2105,11 @@ static int option_probe(struct usb_serial *serial,
>  	if (device_flags & NUMEP2 && iface_desc->bNumEndpoints != 2)
>  		return -ENODEV;
>  
> +	/* Quectel EC25 & EC21 & EG91 & EG95 ... interface 4 can be used as USB network device */
> +	if (serial->dev->descriptor.idVendor == cpu_to_le16(0x2c7c) &&
> +		serial->interface->cur_altsetting->desc.bInterfaceNumber >= 4)
> +		return -ENODEV;

And please use the normal mechanisms for blacklisting interfaces (e.g.
the RSVD() macro).

> +
>  	/* Store the device flags so we can use them during attach. */
>  	usb_set_serial_data(serial, (void *)device_flags);

Also make sure your patches have distinct and descriptive summaries
(Subject lines).

Johan