ALSA: line6: Return error if device not responding

Put an upper bound on how long we will wait for the device to respond to
a read/write request (i.e., 100 milliseconds) and return an error if
this is reached.

Signed-off-by: Chris Rorvick <chris@rorvick.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/sound/usb/line6/driver.c b/sound/usb/line6/driver.c
index 2f9b74e..f2ee804 100644 (file)
--- a/sound/usb/line6/driver.c
+++ b/sound/usb/line6/driver.c
@@ -297,6 +297,7 @@ static void line6_data_received(struct urb *urb)
 }
 
 #define LINE6_READ_WRITE_STATUS_DELAY 2  /* milliseconds */
+#define LINE6_READ_WRITE_MAX_RETRIES 50
 
 /*
        Read data from device.
@@ -307,6 +308,7 @@ int line6_read_data(struct usb_line6 *line6, int address, void *data,
        struct usb_device *usbdev = line6->usbdev;
        int ret;
        unsigned char len;
+       unsigned count;
 
        /* query the serial number: */
        ret = usb_control_msg(usbdev, usb_sndctrlpipe(usbdev, 0), 0x67,
@@ -320,7 +322,7 @@ int line6_read_data(struct usb_line6 *line6, int address, void *data,
        }
 
        /* Wait for data length. We'll get 0xff until length arrives. */
-       do {
+       for (count = 0; count < LINE6_READ_WRITE_MAX_RETRIES; count++) {
                mdelay(LINE6_READ_WRITE_STATUS_DELAY);
 
                ret = usb_control_msg(usbdev, usb_rcvctrlpipe(usbdev, 0), 0x67,
@@ -333,9 +335,16 @@ int line6_read_data(struct usb_line6 *line6, int address, void *data,
                                "receive length failed (error %d)\n", ret);
                        return ret;
                }
-       } while (len == 0xff);
 
-       if (len != datalen) {
+               if (len != 0xff)
+                       break;
+       }
+
+       if (len == 0xff) {
+               dev_err(line6->ifcdev, "read failed after %d retries\n",
+                       count);
+               return -EIO;
+       } else if (len != datalen) {
                /* should be equal or something went wrong */
                dev_err(line6->ifcdev,
                        "length mismatch (expected %d, got %d)\n",
@@ -367,6 +376,7 @@ int line6_write_data(struct usb_line6 *line6, int address, void *data,
        struct usb_device *usbdev = line6->usbdev;
        int ret;
        unsigned char status;
+       int count;
 
        ret = usb_control_msg(usbdev, usb_sndctrlpipe(usbdev, 0), 0x67,
                              USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_OUT,
@@ -379,7 +389,7 @@ int line6_write_data(struct usb_line6 *line6, int address, void *data,
                return ret;
        }
 
-       do {
+       for (count = 0; count < LINE6_READ_WRITE_MAX_RETRIES; count++) {
                mdelay(LINE6_READ_WRITE_STATUS_DELAY);
 
                ret = usb_control_msg(usbdev, usb_rcvctrlpipe(usbdev, 0),
@@ -394,9 +404,16 @@ int line6_write_data(struct usb_line6 *line6, int address, void *data,
                                "receiving status failed (error %d)\n", ret);
                        return ret;
                }
-       } while (status == 0xff);
 
-       if (status != 0) {
+               if (status != 0xff)
+                       break;
+       }
+
+       if (status == 0xff) {
+               dev_err(line6->ifcdev, "write failed after %d retries\n",
+                       count);
+               return -EIO;
+       } else if (status != 0) {
                dev_err(line6->ifcdev, "write failed (error %d)\n", ret);
                return -EINVAL;
        }