From 8a92ec92c7892633f5bc82aa8d97e4bd80bf3ebd Mon Sep 17 00:00:00 2001 From: Macpaul Lin Date: Wed, 19 Dec 2018 12:11:03 +0800 Subject: cdc-acm: fix abnormal DATA RX issue for Mediatek Preloader. commit eafb27fa5283599ce6c5492ea18cf636a28222bb upstream. Mediatek Preloader is a proprietary embedded boot loader for loading Little Kernel and Linux into device DRAM. This boot loader also handle firmware update. Mediatek Preloader will be enumerated as a virtual COM port when the device is connected to Windows or Linux OS via CDC-ACM class driver. When the USB enumeration has been done, Mediatek Preloader will send out handshake command "READY" to PC actively instead of waiting command from the download tool. Since Linux 4.12, the commit "tty: reset termios state on device registration" (93857edd9829e144acb6c7e72d593f6e01aead66) causes Mediatek Preloader receiving some abnoraml command like "READYXX" as it sent. This will be recognized as an incorrect response. The behavior change also causes the download handshake fail. This change only affects subsequent connects if the reconnected device happens to get the same minor number. By disabling the ECHO termios flag could avoid this problem. However, it cannot be done by user space configuration when download tool open /dev/ttyACM0. This is because the device running Mediatek Preloader will send handshake command "READY" immediately once the CDC-ACM driver is ready. This patch wants to fix above problem by introducing "DISABLE_ECHO" property in driver_info. When Mediatek Preloader is connected, the CDC-ACM driver could disable ECHO flag in termios to avoid the problem. Signed-off-by: Macpaul Lin Cc: stable@vger.kernel.org Reviewed-by: Johan Hovold Acked-by: Oliver Neukum Signed-off-by: Greg Kroah-Hartman --- drivers/usb/class/cdc-acm.c | 10 ++++++++++ 1 file changed, 10 insertions(+) (limited to 'drivers/usb/class/cdc-acm.c') diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c index 0a8e5ac891d4..3919ea066bf9 100644 --- a/drivers/usb/class/cdc-acm.c +++ b/drivers/usb/class/cdc-acm.c @@ -507,6 +507,13 @@ static int acm_tty_install(struct tty_driver *driver, struct tty_struct *tty) if (retval) goto error_init_termios; + /* + * Suppress initial echoing for some devices which might send data + * immediately after acm driver has been installed. + */ + if (acm->quirks & DISABLE_ECHO) + tty->termios.c_lflag &= ~ECHO; + tty->driver_data = acm; return 0; @@ -1677,6 +1684,9 @@ static const struct usb_device_id acm_ids[] = { { USB_DEVICE(0x0e8d, 0x0003), /* FIREFLY, MediaTek Inc; andrey.arapov@gmail.com */ .driver_info = NO_UNION_NORMAL, /* has no union descriptor */ }, + { USB_DEVICE(0x0e8d, 0x2000), /* MediaTek Inc Preloader */ + .driver_info = DISABLE_ECHO, /* DISABLE ECHO in termios flag */ + }, { USB_DEVICE(0x0e8d, 0x3329), /* MediaTek Inc GPS */ .driver_info = NO_UNION_NORMAL, /* has no union descriptor */ }, -- cgit v1.2.3 From 460398af9f97910992f1a3bad215b659229ed8b9 Mon Sep 17 00:00:00 2001 From: Daniele Palmas Date: Fri, 28 Dec 2018 16:15:41 +0100 Subject: usb: cdc-acm: send ZLP for Telit 3G Intel based modems commit 34aabf918717dd14e05051896aaecd3b16b53d95 upstream. Telit 3G Intel based modems require zero packet to be sent if out data size is equal to the endpoint max packet size. Signed-off-by: Daniele Palmas Cc: stable Signed-off-by: Greg Kroah-Hartman --- drivers/usb/class/cdc-acm.c | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'drivers/usb/class/cdc-acm.c') diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c index 3919ea066bf9..736de1021d8b 100644 --- a/drivers/usb/class/cdc-acm.c +++ b/drivers/usb/class/cdc-acm.c @@ -1885,6 +1885,13 @@ static const struct usb_device_id acm_ids[] = { .driver_info = IGNORE_DEVICE, }, + { USB_DEVICE(0x1bc7, 0x0021), /* Telit 3G ACM only composition */ + .driver_info = SEND_ZERO_PACKET, + }, + { USB_DEVICE(0x1bc7, 0x0023), /* Telit 3G ACM + ECM composition */ + .driver_info = SEND_ZERO_PACKET, + }, + /* control interfaces without any protocol set */ { USB_INTERFACE_INFO(USB_CLASS_COMM, USB_CDC_SUBCLASS_ACM, USB_CDC_PROTO_NONE) }, -- cgit v1.2.3