It has been reported that the dummy byte we add to avoid ZLPs can be forwarded by the modem to the PGW/GGSN, and that some operators will drop the connection if this happens. In theory, QMI devices are based on CDC ECM and should as such both support ZLPs and silently ignore the dummy byte. The latter assumption failed. Let's test out the first. Signed-off-by: Bjørn Mork <bjorn@xxxxxxx> --- I am a bit worried about the effect of this change on all the devices I can't test myself. But trying it is the only way we can ever find out.... drivers/net/usb/qmi_wwan.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/net/usb/qmi_wwan.c b/drivers/net/usb/qmi_wwan.c index 304ec6555cd8..1ed00519f29e 100644 --- a/drivers/net/usb/qmi_wwan.c +++ b/drivers/net/usb/qmi_wwan.c @@ -826,7 +826,7 @@ static int qmi_wwan_resume(struct usb_interface *intf) static const struct driver_info qmi_wwan_info = { .description = "WWAN/QMI device", - .flags = FLAG_WWAN, + .flags = FLAG_WWAN | FLAG_SEND_ZLP, .bind = qmi_wwan_bind, .unbind = qmi_wwan_unbind, .manage_power = qmi_wwan_manage_power, @@ -835,7 +835,7 @@ static const struct driver_info qmi_wwan_info = { static const struct driver_info qmi_wwan_info_quirk_dtr = { .description = "WWAN/QMI device", - .flags = FLAG_WWAN, + .flags = FLAG_WWAN | FLAG_SEND_ZLP, .bind = qmi_wwan_bind, .unbind = qmi_wwan_unbind, .manage_power = qmi_wwan_manage_power, -- 2.11.0 -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html