This is a note to let you know that I've just added the patch titled

    USB: cdc-acm: add quirk for control-line state requests

to my usb git tree which can be found at
    git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git
in the usb-linus branch.

The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the
next -rc kernel release.

If you have any questions about this process, please let me know.


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

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 <[email protected]>
Tested-by: Nix <[email protected]>
Cc: stable <[email protected]>     # v3.16
Signed-off-by: Johan Hovold <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
 drivers/usb/class/cdc-acm.c | 14 ++++++++++++--
 drivers/usb/class/cdc-acm.h |  2 ++
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
index 9d6495424b06..077d58ac3dcb 100644
--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -148,8 +148,15 @@ static int acm_ctrl_msg(struct acm *acm, int request, int 
value,
 /* 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) \
@@ -1320,6 +1327,7 @@ 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) {
@@ -1687,6 +1695,8 @@ static const struct usb_device_id acm_ids[] = {
        { 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 */
        },
diff --git a/drivers/usb/class/cdc-acm.h b/drivers/usb/class/cdc-acm.h
index fc75651afe1c..d3251ebd09e2 100644
--- 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)
-- 
2.1.3


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