releases/3.17.3/usb-cdc-acm-add-quirk-for-control-line-state-requests.patch

From 2a8cdfde9237c4e1bd7c2e68c415b006491d23cc Mon Sep 17 00:00:00 2001
From: Johan Hovold <johan@kernel.org>
Date: Thu, 6 Nov 2014 18:08:33 +0100
Subject: USB: cdc-acm: add quirk for control-line state requests

From: Johan Hovold <johan@kernel.org>

commit 2a8cdfde9237c4e1bd7c2e68c415b006491d23cc upstream.

Add new quirk for devices that cannot handle control-line state
requests.

Note that we currently send these requests to all devices, regardless of
whether they claim to support it, but that errors are only logged if
support is claimed.

Since commit 0943d8ead30e ("USB: cdc-acm: use tty-port dtr_rts"), which
only changed the timings for these requests slightly, this has been
reported to cause occasional firmware crashes on Simtec Electronics
Entropy Key devices after re-enumeration. Enable the quirk for this
device.

Reported-by: Nix <nix@esperi.org.uk>
Tested-by: Nix <nix@esperi.org.uk>
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/usb/class/cdc-acm.c |   14 ++++++++++++--
 drivers/usb/class/cdc-acm.h |    2 ++
 2 files changed, 14 insertions(+), 2 deletions(-)

--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -145,8 +145,15 @@ static int acm_ctrl_msg(struct acm *acm,
 /* devices aren't required to support these requests.
  * the cdc acm descriptor tells whether they do...
  */
-#define acm_set_control(acm, control) \
-	acm_ctrl_msg(acm, USB_CDC_REQ_SET_CONTROL_LINE_STATE, control, NULL, 0)
+static inline int acm_set_control(struct acm *acm, int control)
+{
+	if (acm->quirks & QUIRK_CONTROL_LINE_STATE)
+		return -EOPNOTSUPP;
+
+	return acm_ctrl_msg(acm, USB_CDC_REQ_SET_CONTROL_LINE_STATE,
+			control, NULL, 0);
+}
+
 #define acm_set_line(acm, line) \
 	acm_ctrl_msg(acm, USB_CDC_REQ_SET_LINE_CODING, 0, line, sizeof *(line))
 #define acm_send_break(acm, ms) \
@@ -1315,6 +1322,7 @@ made_compressed_probe:
 	tty_port_init(&acm->port);
 	acm->port.ops = &acm_port_ops;
 	init_usb_anchor(&acm->delayed);
+	acm->quirks = quirks;
 
 	buf = usb_alloc_coherent(usb_dev, ctrlsize, GFP_KERNEL, &acm->ctrl_dma);
 	if (!buf) {
@@ -1682,6 +1690,8 @@ static const struct usb_device_id acm_id
 	{ USB_DEVICE(0x0572, 0x1328), /* Shiro / Aztech USB MODEM UM-3100 */
 	.driver_info = NO_UNION_NORMAL, /* has no union descriptor */
 	},
+	{ USB_DEVICE(0x20df, 0x0001), /* Simtec Electronics Entropy Key */
+	.driver_info = QUIRK_CONTROL_LINE_STATE, },
 	{ USB_DEVICE(0x2184, 0x001c) },	/* GW Instek AFG-2225 */
 	{ USB_DEVICE(0x22b8, 0x6425), /* Motorola MOTOMAGX phones */
 	},
--- a/drivers/usb/class/cdc-acm.h
+++ b/drivers/usb/class/cdc-acm.h
@@ -121,6 +121,7 @@ struct acm {
 	unsigned int throttle_req:1;			/* throttle requested */
 	u8 bInterval;
 	struct usb_anchor delayed;			/* writes queued for a device about to be woken */
+	unsigned long quirks;
 };
 
 #define CDC_DATA_INTERFACE_TYPE	0x0a
@@ -132,3 +133,4 @@ struct acm {
 #define NOT_A_MODEM			BIT(3)
 #define NO_DATA_INTERFACE		BIT(4)
 #define IGNORE_DEVICE			BIT(5)
+#define QUIRK_CONTROL_LINE_STATE	BIT(6)