net/cdc_ncm: Enable ZLP for DisplayLink ethernet devices

This improves performance and stability of
DL-3xxx/DL-5xxx/DL-6xxx device series.

Specifically prevents device from temporary network dropouts when
playing video from the web and network traffic going through is high.

Signed-off-by: Dominik Czerwik <dominik.czerwik@synaptics.com>
Signed-off-by: Łukasz Spintzyk <lukasz.spintzyk@synaptics.com>
Link: https://lore.kernel.org/r/20220720060518.541-1-lukasz.spintzyk@synaptics.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

diff --git a/drivers/net/usb/cdc_ncm.c b/drivers/net/usb/cdc_ncm.c
index d55f59c..8d5cbda 100644 (file)
--- a/drivers/net/usb/cdc_ncm.c
+++ b/drivers/net/usb/cdc_ncm.c
@@ -1892,7 +1892,7 @@ static void cdc_ncm_status(struct usbnet *dev, struct urb *urb)
 }
 
 static const struct driver_info cdc_ncm_info = {
-       .description = "CDC NCM",
+       .description = "CDC NCM (NO ZLP)",
        .flags = FLAG_POINTTOPOINT | FLAG_NO_SETINT | FLAG_MULTI_PACKET
                        | FLAG_LINK_INTR | FLAG_ETHER,
        .bind = cdc_ncm_bind,
@@ -1904,6 +1904,19 @@ static const struct driver_info cdc_ncm_info = {
        .set_rx_mode = usbnet_cdc_update_filter,
 };
 
+/* Same as cdc_ncm_info, but with FLAG_SEND_ZLP  */
+static const struct driver_info cdc_ncm_zlp_info = {
+       .description = "CDC NCM (SEND ZLP)",
+       .flags = FLAG_POINTTOPOINT | FLAG_NO_SETINT | FLAG_MULTI_PACKET
+                       | FLAG_LINK_INTR | FLAG_ETHER | FLAG_SEND_ZLP,
+       .bind = cdc_ncm_bind,
+       .unbind = cdc_ncm_unbind,
+       .manage_power = usbnet_manage_power,
+       .status = cdc_ncm_status,
+       .rx_fixup = cdc_ncm_rx_fixup,
+       .tx_fixup = cdc_ncm_tx_fixup,
+};
+
 /* Same as cdc_ncm_info, but with FLAG_WWAN */
 static const struct driver_info wwan_info = {
        .description = "Mobile Broadband Network Device",
@@ -2010,6 +2023,16 @@ static const struct usb_device_id cdc_devs[] = {
          .driver_info = (unsigned long)&wwan_info,
        },
 
+       /* DisplayLink docking stations */
+       { .match_flags = USB_DEVICE_ID_MATCH_INT_INFO
+               | USB_DEVICE_ID_MATCH_VENDOR,
+         .idVendor = 0x17e9,
+         .bInterfaceClass = USB_CLASS_COMM,
+         .bInterfaceSubClass = USB_CDC_SUBCLASS_NCM,
+         .bInterfaceProtocol = USB_CDC_PROTO_NONE,
+         .driver_info = (unsigned long)&cdc_ncm_zlp_info,
+       },
+
        /* Generic CDC-NCM devices */
        { USB_INTERFACE_INFO(USB_CLASS_COMM,
                USB_CDC_SUBCLASS_NCM, USB_CDC_PROTO_NONE),