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 <nix@esperi.org.uk>
Tested-by: Nix <nix@esperi.org.uk>
Cc: stable <stable@vger.kernel.org>	# v3.16
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
index 9d64954..077d58a 100644 (file)
--- 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 fc75651..d3251eb 100644 (file)
--- 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)