staging/easycap: Improve interface to the videodev module

The changes here represent an intermediate step towards bringing the
driver within the V4L2 framework.

Signed-off-by: Mike Thomas <rmthomas@sciolus.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

5 files changed, 287 insertions, 72 deletions

diff --git a/drivers/staging/easycap/README b/drivers/staging/easycap/README
index 3775481f05e..6b5ac0d34bd 100644
--- a/drivers/staging/easycap/README
+++ b/drivers/staging/easycap/README
@@ -24,6 +24,9 @@ Two kinds of EasyCAP have this USB ID, namely:
 BUILD OPTIONS AND DEPENDENCIES
 ------------------------------
 
+Unless EASYCAP_DEBUG is defined during compilation it will not be possible
+to select a debug level at the time of module installation.
+
 If the parameter EASYCAP_IS_VIDEODEV_CLIENT is undefined during compilation
 the built module is entirely independent of the videodev module, and when
 the EasyCAP is physically plugged into a USB port the special files
@@ -33,41 +36,54 @@ respectively.
 If the parameter EASYCAP_IS_VIDEODEV_CLIENT is defined during compilation
 the built easycap module is configured to register with the videodev module,
 in which case the special files created when the EasyCAP is plugged in are
-/dev/video0 and /dev/easysnd0.  Use of the easycap module as a client of
-the videodev module has received very little testing as of June 2010.
+/dev/video0 and /dev/easysnd0.
+
+During in-tree builds the following should should be defined whenever the
+parameter EASYCAP_IS_VIDEODEV_CLIENT is defined:
+
+EASYCAP_NEEDS_V4L2_DEVICE_H
+EASYCAP_NEEDS_V4L2_FOPS
+EASYCAP_NEEDS_UNLOCKED_IOCTL
+
+If the build is performed out-of-tree against older kernels the parameters
+to be defined depend on the kernel version in a way which will not be
+discussed here.
 
 
-KNOWN BUILD PROBLEMS
+KNOWN RUNTIME ISSUES
 --------------------
 
-(1) Recent gcc versions may generate the message:
+(1) Intentionally, this driver will not stream material which is unambiguously
+identified by the hardware as copy-protected.  Normal video output will be
+present for about a minute but will then freeze when this situation arises.
 
-     warning: the frame size of .... bytes is larger than 1024 bytes
+(2) The controls for luminance, contrast, saturation, hue and volume may not
+always work properly.
 
-This warning can be suppressed by specifying in the Makefile:
+(3) Reduced-resolution S-Video seems to suffer from moire artefacts.
 
-     EXTRA_CFLAGS += -Wframe-larger-than=8192
 
-but it would be preferable to remove the cause of the warning.
+INPUT NUMBERING
+---------------
 
+For the EasyCAP with S-VIDEO input cable the driver regards a request for
+inputs numbered 0 or 1 as referring to CVBS and a request for input
+numbered 5 as referring to S-VIDEO.
 
-KNOWN RUNTIME ISSUES
---------------------
+For the EasyCAP with four CVBS inputs the driver expects to be asked for
+any one of inputs numbered 1,2,3,4.  If input 0 is asked for, it is
+interpreted as input 1.
 
-(1) Randomly (maybe 5 to 10% of occasions) the driver fails to produce any
-output at start-up.  Closing mplayer (or whatever the user program is) and
-restarting it restores normal performance without any other remedial action
-being necessary.  The reason for this is not known.
 
-(2) Intentionally, this driver will not stream material which is unambiguously
-identified by the hardware as copy-protected.  The video output will freeze
-within about a minute when this situation arises.
+MODULE PARAMETERS
+-----------------
 
-(3) The controls for luminance, contrast, saturation, hue and volume may not
-always work properly.
+Three module parameters are defined:
 
-(4) Reduced-resolution S-Video seems to suffer from moire artefacts.  No
-attempt has yet been made to rememdy this.
+debug      the easycap module is configured at diagnostic level n (0 to 9)
+gain       audio gain level n (0 to 31, default is 16)
+bars       0 =>  testcard bars when incoming video signal is lost
+           1 =>  testcard bars when incoming video signal is lost (default)
 
 
 SUPPORTED TV STANDARDS AND RESOLUTIONS
@@ -82,18 +98,29 @@ usable as (for example) the "norm=" parameter in the mplayer command:
     PAL_60,       NTSC_443,
     PAL_M.
 
+In addition, the driver offers "custom" pseudo-standards with a framerate
+which is 20% of the usual framerate.  These pseudo-standards are named:
+
+    PAL_BGHIN_SLOW,    NTSC_N_443_SLOW,
+    PAL_Nc_SLOW,       NTSC_N_SLOW,
+    SECAM_SLOW,        NTSC_M_SLOW,        NTSC_M_JP_SLOW,
+    PAL_60_SLOW,       NTSC_443_SLOW,
+    PAL_M_SLOW.
+
+
 The available picture sizes are:
 
      at 25 frames per second:   720x576, 704x576, 640x480, 360x288, 320x240;
-     at 30 frames per second:   720x480, 640x480, 360x240, 320x240;
+     at 30 frames per second:   720x480, 640x480, 360x240, 320x240.
 
 
 WHAT'S TESTED AND WHAT'S NOT
 ----------------------------
 
-This driver is known to work with mplayer, mencoder, tvtime and sufficiently
-recent versions of vlc.  An interface to ffmpeg is implemented, but serious
-audio-video synchronization problems remain.
+This driver is known to work with mplayer, mencoder, tvtime, zoneminder,
+xawtv, gstreamer and sufficiently recent versions of vlc.  An interface
+to ffmpeg is implemented, but serious audio-video synchronization problems
+remain.
 
 The driver is designed to support all the TV standards accepted by the
 hardware, but as yet it has actually been tested on only a few of these.
@@ -101,10 +128,7 @@ hardware, but as yet it has actually been tested on only a few of these.
 I have been unable to test and calibrate the S-video input myself because I
 do not possess any equipment with S-video output.
 
-This driver does not understand the V4L1 IOCTL commands, so programs such
-as camorama are not compatible.  There are reports that the driver does
-work with sufficiently recent (V4L2) versions of zoneminder, but I have not
-attempted to confirm this myself.
+This driver does not understand the V4L1 IOCTL commands.
 
 
 UDEV RULES
@@ -120,6 +144,17 @@ ATTRS{idVendor}=="05e1", ATTRS{idProduct}=="0408", \
 LABEL="easycap_rules_end"
 
 
+MODPROBE CONFIGURATION
+----------------------
+
+The easycap module is in competition with the module snd-usb-audio for the
+EasyCAP's audio channel, and its installation can be aided by providing a
+file in directory /etc/modprobe.d with content:
+
+options easycap  gain=16 bars=1
+install easycap /sbin/rmmod snd-usb-audio; /sbin/modprobe --ignore-install easycap
+
+
 ACKNOWLEGEMENTS AND REFERENCES
 ------------------------------
 This driver makes use of information contained in the Syntek Semicon DC-1125
diff --git a/drivers/staging/easycap/easycap.h b/drivers/staging/easycap/easycap.h
index 762c6cea54c..cc8e8c581ae 100644
--- a/drivers/staging/easycap/easycap.h
+++ b/drivers/staging/easycap/easycap.h
@@ -33,6 +33,7 @@
  *                EASYCAP_NEEDS_USBVIDEO_H
  *                EASYCAP_NEEDS_V4L2_DEVICE_H
  *                EASYCAP_NEEDS_V4L2_FOPS
+ *                EASYCAP_NEEDS_UNLOCKED_IOCTL
  *
  *  IF REQUIRED THEY MUST BE EXTERNALLY DEFINED, FOR EXAMPLE AS COMPILER
  *  OPTIONS.
@@ -81,25 +82,14 @@
 
 /*vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv*/
 #if defined(EASYCAP_IS_VIDEODEV_CLIENT)
-#if (!defined(__OLD_VIDIOC_))
-#define __OLD_VIDIOC_
-#endif /* !defined(__OLD_VIDIOC_) */
-
 #include <media/v4l2-dev.h>
-
 #if defined(EASYCAP_NEEDS_V4L2_DEVICE_H)
 #include <media/v4l2-device.h>
 #endif /*EASYCAP_NEEDS_V4L2_DEVICE_H*/
 #endif /*EASYCAP_IS_VIDEODEV_CLIENT*/
 /*^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^*/
-
-#if (!defined(__OLD_VIDIOC_))
-#define __OLD_VIDIOC_
-#endif /* !defined(__OLD_VIDIOC_) */
 #include <linux/videodev2.h>
-
 #include <linux/soundcard.h>
-
 #if defined(EASYCAP_NEEDS_USBVIDEO_H)
 #include <config/video/usbvideo.h>
 #endif /*EASYCAP_NEEDS_USBVIDEO_H*/
@@ -110,7 +100,6 @@
 
 #define STRINGIZE_AGAIN(x) #x
 #define STRINGIZE(x) STRINGIZE_AGAIN(x)
-
 /*---------------------------------------------------------------------------*/
 /*  VENDOR, PRODUCT:  Syntek Semiconductor Co., Ltd
  *
@@ -305,6 +294,8 @@ int hue_ok;
  */
 /*---------------------------------------------------------------------------*/
 struct easycap {
+#define TELLTALE "expectedstring"
+char telltale[16];
 int isdongle;
 
 /*vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv*/
@@ -501,7 +492,6 @@ long             easycap_ioctl_noinode(struct file *, unsigned int, \
                                                                 unsigned long);
 int              easycap_ioctl(struct inode *, struct file *, unsigned int, \
                                                                 unsigned long);
-
 /*vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv*/
 #if defined(EASYCAP_IS_VIDEODEV_CLIENT)
 int              easycap_open_noinode(struct file *);
diff --git a/drivers/staging/easycap/easycap_ioctl.c b/drivers/staging/easycap/easycap_ioctl.c
index 2f9b3eab489..447953a4e80 100644
--- a/drivers/staging/easycap/easycap_ioctl.c
+++ b/drivers/staging/easycap/easycap_ioctl.c
@@ -977,9 +977,13 @@ if (NULL == file) {
 }
 peasycap = file->private_data;
 if (NULL == peasycap) {
-        SAY("ERROR:  peasycap is NULL.\n");
+        SAY("ERROR:  peasycap is NULL\n");
         return -1;
 }
+if (memcmp(&peasycap->telltale[0], TELLTALE, strlen(TELLTALE))) {
+        SAY("ERROR: bad peasycap\n");
+        return -EFAULT;
+}
 p = peasycap->pusb_device;
 if (NULL == p) {
         SAM("ERROR: peasycap->pusb_device is NULL\n");
@@ -1012,6 +1016,11 @@ if (0 <= kd && DONGLE_MANY > kd) {
                 mutex_unlock(&easycap_dongle[kd].mutex_video);
                 return -ERESTARTSYS;
         }
+        if (memcmp(&peasycap->telltale[0], TELLTALE, strlen(TELLTALE))) {
+                SAY("ERROR: bad peasycap\n");
+                mutex_unlock(&easycap_dongle[kd].mutex_video);
+                return -EFAULT;
+        }
         p = peasycap->pusb_device;
         if (NULL == peasycap->pusb_device) {
                 SAM("ERROR: peasycap->pusb_device is NULL\n");
@@ -2297,7 +2306,7 @@ case VIDIOC_DQBUF:
                                 ((long long int)(timeval.tv_sec - \
                                                 timeval2.tv_sec)) + \
                                 (long long int)(timeval.tv_usec - \
-                                timeval2.tv_usec);
+                                                timeval2.tv_usec);
                 sdr = signed_div(fudge, 1000);
                 sll = sdr.quotient;
                 ull = sdr.remainder;
@@ -2317,6 +2326,8 @@ case VIDIOC_DQBUF:
         JOM(16, "  %10i=bytesused\n", v4l2_buffer.bytesused);
         JOM(16, "  0x%08X=flags\n", v4l2_buffer.flags);
         JOM(16, "  %10i=field\n", v4l2_buffer.field);
+        JOM(16, "  %10li=timestamp.tv_sec\n", \
+                                        (long)v4l2_buffer.timestamp.tv_sec);
         JOM(16, "  %10li=timestamp.tv_usec\n", \
                                         (long)v4l2_buffer.timestamp.tv_usec);
         JOM(16, "  %10i=sequence\n", v4l2_buffer.sequence);
@@ -2528,6 +2539,10 @@ if (NULL == peasycap) {
         SAY("ERROR:  peasycap is NULL.\n");
         return -EFAULT;
 }
+if (memcmp(&peasycap->telltale[0], TELLTALE, strlen(TELLTALE))) {
+        SAY("ERROR: bad peasycap\n");
+        return -EFAULT;
+}
 p = peasycap->pusb_device;
 if (NULL == p) {
         SAM("ERROR: peasycap->pusb_device is NULL\n");
@@ -2560,6 +2575,11 @@ if (0 <= kd && DONGLE_MANY > kd) {
                 mutex_unlock(&easycap_dongle[kd].mutex_audio);
                 return -ERESTARTSYS;
         }
+        if (memcmp(&peasycap->telltale[0], TELLTALE, strlen(TELLTALE))) {
+                SAY("ERROR: bad peasycap\n");
+                mutex_unlock(&easycap_dongle[kd].mutex_audio);
+                return -EFAULT;
+        }
         p = peasycap->pusb_device;
         if (NULL == peasycap->pusb_device) {
                 SAM("ERROR: peasycap->pusb_device is NULL\n");
@@ -2795,3 +2815,5 @@ mutex_unlock(&easycap_dongle[kd].mutex_audio);
 return 0;
 }
 /*****************************************************************************/
+
+
diff --git a/drivers/staging/easycap/easycap_main.c b/drivers/staging/easycap/easycap_main.c
index 67ae755fcfa..25e41784f4e 100644
--- a/drivers/staging/easycap/easycap_main.c
+++ b/drivers/staging/easycap/easycap_main.c
@@ -93,16 +93,15 @@ const struct file_operations easycap_fops = {
         .llseek         = no_llseek,
 };
 struct vm_operations_struct easycap_vm_ops = {
-.open  = easycap_vma_open,
-.close = easycap_vma_close,
-.fault = easycap_vma_fault,
+        .open  = easycap_vma_open,
+        .close = easycap_vma_close,
+        .fault = easycap_vma_fault,
 };
 struct usb_class_driver easycap_class = {
-.name = "usb/easycap%d",
-.fops = &easycap_fops,
-.minor_base = USB_SKEL_MINOR_BASE,
+        .name = "usb/easycap%d",
+        .fops = &easycap_fops,
+        .minor_base = USB_SKEL_MINOR_BASE,
 };
-
 /*vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv*/
 #if defined(EASYCAP_IS_VIDEODEV_CLIENT)
 #if defined(EASYCAP_NEEDS_V4L2_FOPS)
@@ -121,7 +120,6 @@ const struct v4l2_file_operations v4l2_fops = {
 #endif /*EASYCAP_NEEDS_V4L2_FOPS*/
 #endif /*EASYCAP_IS_VIDEODEV_CLIENT*/
 /*^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^*/
-
 /*--------------------------------------------------------------------------*/
 /*
  *  PARAMETERS USED WHEN REGISTERING THE AUDIO INTERFACE
@@ -147,7 +145,7 @@ struct usb_class_driver easysnd_class = {
 /****************************************************************************/
 /*---------------------------------------------------------------------------*/
 /*
- *  THIS ROUTINE DOES NOT DETECT MULTIPLE OCCURRENCES OF POINTER peasycap
+ *  THIS ROUTINE DOES NOT DETECT DUPLICATE OCCURRENCES OF POINTER peasycap
 */
 /*---------------------------------------------------------------------------*/
 int
@@ -215,6 +213,10 @@ if (NULL == peasycap) {
         SAY("ERROR: peasycap is NULL\n");
         return -EFAULT;
 }
+if (memcmp(&peasycap->telltale[0], TELLTALE, strlen(TELLTALE))) {
+        SAY("ERROR: bad peasycap: 0x%08lX\n", (unsigned long int) peasycap);
+        return -EFAULT;
+}
 if (NULL == peasycap->pusb_device) {
         SAM("ERROR: peasycap->pusb_device is NULL\n");
         return -EFAULT;
@@ -838,6 +840,10 @@ if (NULL == peasycap) {
         SAY("ending unsuccessfully\n");
         return -EFAULT;
 }
+if (memcmp(&peasycap->telltale[0], TELLTALE, strlen(TELLTALE))) {
+        SAY("ERROR: bad peasycap: 0x%08lX\n", (unsigned long int) peasycap);
+        return -EFAULT;
+}
 if (0 != kill_video_urbs(peasycap)) {
         SAM("ERROR: kill_video_urbs() failed\n");
         return -EFAULT;
@@ -867,6 +873,10 @@ if (NULL == peasycap) {
         SAY("ending unsuccessfully\n");
         return -EFAULT;
 }
+if (memcmp(&peasycap->telltale[0], TELLTALE, strlen(TELLTALE))) {
+        SAY("ERROR: bad peasycap: 0x%08lX\n", (unsigned long int) peasycap);
+        return -EFAULT;
+}
 if (0 != kill_video_urbs(peasycap)) {
         SAM("ERROR: kill_video_urbs() failed\n");
         return -EFAULT;
@@ -904,6 +914,10 @@ if (NULL == peasycap) {
         SAM("ERROR: peasycap is NULL: cannot perform deletions\n");
         return;
 }
+if (memcmp(&peasycap->telltale[0], TELLTALE, strlen(TELLTALE))) {
+        SAY("ERROR: bad peasycap: 0x%08lX\n", (unsigned long int) peasycap);
+        return;
+}
 kd = isdongle(peasycap);
 /*---------------------------------------------------------------------------*/
 /*
@@ -1026,8 +1040,6 @@ if ((struct list_head *)NULL != peasycap->purb_audio_head) {
 JOM(4, "%i audio data_urb structures freed\n", m);
 JOM(4, "setting peasycap->purb_audio_head=NULL\n");
 peasycap->purb_audio_head = (struct list_head *)NULL;
-} else {
-JOM(4, "peasycap->purb_audio_head is NULL\n");
 }
 /*---------------------------------------------------------------------------*/
 JOM(4, "freeing audio isoc buffers.\n");
@@ -1108,6 +1120,10 @@ if (NULL == peasycap) {
         SAY("ERROR:  peasycap is NULL\n");
         return -EFAULT;
 }
+if (memcmp(&peasycap->telltale[0], TELLTALE, strlen(TELLTALE))) {
+        SAY("ERROR: bad peasycap: 0x%08lX\n", (unsigned long int) peasycap);
+        return -EFAULT;
+}
 if (NULL == peasycap->pusb_device) {
         SAY("ERROR:  peasycap->pusb_device is NULL\n");
         return -EFAULT;
@@ -1140,10 +1156,16 @@ if (0 <= kd && DONGLE_MANY > kd) {
                 mutex_unlock(&easycap_dongle[kd].mutex_video);
                 return -ERESTARTSYS;
         }
+        if (memcmp(&peasycap->telltale[0], TELLTALE, strlen(TELLTALE))) {
+                SAY("ERROR: bad peasycap: 0x%08lX\n", \
+                                                (unsigned long int) peasycap);
+                mutex_unlock(&easycap_dongle[kd].mutex_video);
+                return -ERESTARTSYS;
+        }
         if (NULL == peasycap->pusb_device) {
                 SAM("ERROR: peasycap->pusb_device is NULL\n");
                 mutex_unlock(&easycap_dongle[kd].mutex_video);
-        return -ERESTARTSYS;
+                return -ERESTARTSYS;
         }
 } else
         /*-------------------------------------------------------------------*/
@@ -2687,11 +2709,16 @@ easycap_vma_open(struct vm_area_struct *pvma)
 struct easycap *peasycap;
 
 peasycap = pvma->vm_private_data;
-if (NULL != peasycap)
-        peasycap->vma_many++;
-
+if (NULL == peasycap) {
+        SAY("ERROR: peasycap is NULL\n");
+        return;
+}
+if (memcmp(&peasycap->telltale[0], TELLTALE, strlen(TELLTALE))) {
+        SAY("ERROR: bad peasycap: 0x%08lX\n", (unsigned long int) peasycap);
+        return;
+}
+peasycap->vma_many++;
 JOT(8, "%i=peasycap->vma_many\n", peasycap->vma_many);
-
 return;
 }
 /*****************************************************************************/
@@ -2701,10 +2728,16 @@ easycap_vma_close(struct vm_area_struct *pvma)
 struct easycap *peasycap;
 
 peasycap = pvma->vm_private_data;
-if (NULL != peasycap) {
-        peasycap->vma_many--;
-        JOT(8, "%i=peasycap->vma_many\n", peasycap->vma_many);
+if (NULL == peasycap) {
+        SAY("ERROR: peasycap is NULL\n");
+        return;
+}
+if (memcmp(&peasycap->telltale[0], TELLTALE, strlen(TELLTALE))) {
+        SAY("ERROR: bad peasycap: 0x%08lX\n", (unsigned long int) peasycap);
+        return;
 }
+peasycap->vma_many--;
+JOT(8, "%i=peasycap->vma_many\n", peasycap->vma_many);
 return;
 }
 /*****************************************************************************/
@@ -2820,10 +2853,12 @@ if (NULL == peasycap) {
         SAY("ERROR: easycap_complete(): peasycap is NULL\n");
         return;
 }
-
+if (memcmp(&peasycap->telltale[0], TELLTALE, strlen(TELLTALE))) {
+        SAY("ERROR: bad peasycap: 0x%08lX\n", (unsigned long int) peasycap);
+        return;
+}
 if (peasycap->video_eof)
         return;
-
 for (i = 0; i < VIDEO_ISOC_BUFFER_MANY; i++)
         if (purb->transfer_buffer == peasycap->video_isoc_buffer[i].pgo)
                 break;
@@ -3545,6 +3580,7 @@ if (0 == bInterfaceNumber) {
  *  PERFORM URGENT INTIALIZATIONS ...
 */
 /*---------------------------------------------------------------------------*/
+        strcpy(&peasycap->telltale[0], TELLTALE);
         kref_init(&peasycap->kref);
         JOM(8, "intf[%i]: after kref_init(..._video) " \
                         "%i=peasycap->kref.refcount.counter\n", \
@@ -4299,6 +4335,26 @@ case 0: {
  */
 /*--------------------------------------------------------------------------*/
         usb_set_intfdata(pusb_interface, peasycap);
+/*---------------------------------------------------------------------------*/
+/*
+ *  IT IS ESSENTIAL TO INITIALIZE THE HARDWARE BEFORE, RATHER THAN AFTER,
+ *  THE DEVICE IS REGISTERED, BECAUSE SOME VERSIONS OF THE videodev MODULE
+ *  CALL easycap_open() IMMEDIATELY AFTER REGISTRATION, CAUSING A CLASH.
+ *  BEWARE.
+*/
+/*---------------------------------------------------------------------------*/
+#if defined(PREFER_NTSC)
+        peasycap->ntsc = true;
+        JOM(8, "defaulting initially to NTSC\n");
+#else
+        peasycap->ntsc = false;
+        JOM(8, "defaulting initially to PAL\n");
+#endif /*PREFER_NTSC*/
+        rc = reset(peasycap);
+        if (0 != rc) {
+                SAM("ERROR: reset() returned %i\n", rc);
+                return -EFAULT;
+        }
 /*--------------------------------------------------------------------------*/
 /*
  *  THE VIDEO DEVICE CAN BE REGISTERED NOW, AS IT IS READY.
@@ -4687,6 +4743,13 @@ struct easycap *peasycap;
 struct list_head *plist_head;
 struct data_urb *pdata_urb;
 int minor, m, kd;
+/*vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv*/
+#if defined(EASYCAP_IS_VIDEODEV_CLIENT)
+#if defined(EASYCAP_NEEDS_V4L2_DEVICE_H)
+struct v4l2_device *pv4l2_device;
+#endif /*EASYCAP_NEEDS_V4L2_DEVICE_H*/
+#endif /*EASYCAP_IS_VIDEODEV_CLIENT*/
+/*^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^*/
 
 JOT(4, "\n");
 
@@ -4717,6 +4780,38 @@ if (NULL == peasycap) {
         return;
 }
 /*---------------------------------------------------------------------------*/
+#if (!defined(EASYCAP_IS_VIDEODEV_CLIENT))
+#
+/*vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv*/
+#else
+#if defined(EASYCAP_NEEDS_V4L2_DEVICE_H)
+/*---------------------------------------------------------------------------*/
+/*
+ *  SOME VERSIONS OF THE videodev MODULE OVERWRITE THE DATA WHICH HAS
+ *  BEEN WRITTEN BY THE CALL TO usb_set_intfdata() IN easycap_usb_probe(),
+ *  REPLACING IT WITH A POINTER TO THE EMBEDDED v4l2_device STRUCTURE.
+ *  TO DETECT THIS, THE STRING IN THE easycap.telltale[] BUFFER IS CHECKED.
+*/
+/*---------------------------------------------------------------------------*/
+if (memcmp(&peasycap->telltale[0], TELLTALE, strlen(TELLTALE))) {
+        pv4l2_device = usb_get_intfdata(pusb_interface);
+        if ((struct v4l2_device *)NULL == pv4l2_device) {
+                SAY("ERROR: pv4l2_device is NULL\n");
+                return;
+        }
+        peasycap = (struct easycap *) \
+                container_of(pv4l2_device, struct easycap, v4l2_device);
+}
+#endif /*EASYCAP_NEEDS_V4L2_DEVICE_H*/
+#
+#endif /*EASYCAP_IS_VIDEODEV_CLIENT*/
+/*^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^*/
+/*---------------------------------------------------------------------------*/
+if (memcmp(&peasycap->telltale[0], TELLTALE, strlen(TELLTALE))) {
+        SAY("ERROR: bad peasycap: 0x%08lX\n", (unsigned long int) peasycap);
+        return;
+}
+/*---------------------------------------------------------------------------*/
 /*
  *  IF THE WAIT QUEUES ARE NOT CLEARED A DEADLOCK IS POSSIBLE.  BEWARE.
 */
@@ -4806,14 +4901,28 @@ case 0: {
                 JOM(4, "intf[%i]: usb_deregister_dev()\n", bInterfaceNumber);
                 SAM("easycap detached from minor #%d\n", minor);
         }
-/*vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv*/
+/*vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv*/
 #else
+#if defined(EASYCAP_NEEDS_V4L2_DEVICE_H)
+        if (!peasycap->v4l2_device.name[0]) {
+                SAM("ERROR: peasycap->v4l2_device.name is empty\n");
+                if (0 <= kd && DONGLE_MANY > kd)
+                        mutex_unlock(&easycap_dongle[kd].mutex_video);
+                return;
+        }
+        v4l2_device_disconnect(&peasycap->v4l2_device);
+        JOM(4, "v4l2_device_disconnect() OK\n");
+        v4l2_device_unregister(&peasycap->v4l2_device);
+        JOM(4, "v4l2_device_unregister() OK\n");
+#endif /*EASYCAP_NEEDS_V4L2_DEVICE_H*/
+
         video_unregister_device(&peasycap->video_device);
-        JOM(4, "unregistered with videodev: %i=minor\n", \
-                                                peasycap->video_device.minor);
+        JOM(4, "intf[%i]: video_unregister_device() OK\n", bInterfaceNumber);
         (peasycap->registered_video)--;
-/*^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^*/
+        JOM(4, "unregistered with videodev: %i=minor\n", minor);
 #endif /*EASYCAP_IS_VIDEODEV_CLIENT*/
+/*^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^*/
+
         if (0 <= kd && DONGLE_MANY > kd) {
                 mutex_unlock(&easycap_dongle[kd].mutex_video);
                 JOM(4, "unlocked easycap_dongle[%i].mutex_video\n", kd);
@@ -4941,7 +5050,7 @@ MODULE_AUTHOR("R.M. Thomas <rmthomas@sciolus.org>");
 MODULE_DESCRIPTION(EASYCAP_DRIVER_DESCRIPTION);
 MODULE_VERSION(EASYCAP_DRIVER_VERSION);
 #if defined(EASYCAP_DEBUG)
-MODULE_PARM_DESC(debug, "Debug level: 0 (default),1,2,...");
+MODULE_PARM_DESC(debug, "Debug level: 0(default),1,2,...,9");
 #endif /*EASYCAP_DEBUG*/
 MODULE_PARM_DESC(bars, \
         "Testcard bars on input signal failure: 0=>no, 1=>yes(default)");
diff --git a/drivers/staging/easycap/easycap_sound.c b/drivers/staging/easycap/easycap_sound.c
index dc97516cca4..24d8bb4e449 100644
--- a/drivers/staging/easycap/easycap_sound.c
+++ b/drivers/staging/easycap/easycap_sound.c
@@ -64,6 +64,11 @@ if (NULL == peasycap) {
         SAY("ERROR: peasycap is NULL\n");
         return;
 }
+if (memcmp(&peasycap->telltale[0], TELLTALE, strlen(TELLTALE))) {
+        SAY("ERROR: bad peasycap\n");
+        return;
+}
+
 much = 0;
 
 if (peasycap->audio_idle) {
@@ -595,6 +600,13 @@ easysnd_open(struct inode *inode, struct file *file)
 struct usb_interface *pusb_interface;
 struct easycap *peasycap;
 int subminor, rc;
+/*vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv*/
+#if defined(EASYCAP_IS_VIDEODEV_CLIENT)
+#if defined(EASYCAP_NEEDS_V4L2_DEVICE_H)
+struct v4l2_device *pv4l2_device;
+#endif /*EASYCAP_NEEDS_V4L2_DEVICE_H*/
+#endif /*EASYCAP_IS_VIDEODEV_CLIENT*/
+/*^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^*/
 
 JOT(4, "begins\n");
 
@@ -612,6 +624,39 @@ if (NULL == peasycap) {
         SAY("ending unsuccessfully\n");
         return -1;
 }
+/*---------------------------------------------------------------------------*/
+#if (!defined(EASYCAP_IS_VIDEODEV_CLIENT))
+#
+/*vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv*/
+#else
+#if defined(EASYCAP_NEEDS_V4L2_DEVICE_H)
+/*---------------------------------------------------------------------------*/
+/*
+ *  SOME VERSIONS OF THE videodev MODULE OVERWRITE THE DATA WHICH HAS
+ *  BEEN WRITTEN BY THE CALL TO usb_set_intfdata() IN easycap_usb_probe(),
+ *  REPLACING IT WITH A POINTER TO THE EMBEDDED v4l2_device STRUCTURE.
+ *  TO DETECT THIS, THE STRING IN THE easycap.telltale[] BUFFER IS CHECKED.
+*/
+/*---------------------------------------------------------------------------*/
+if (memcmp(&peasycap->telltale[0], TELLTALE, strlen(TELLTALE))) {
+        pv4l2_device = usb_get_intfdata(pusb_interface);
+        if ((struct v4l2_device *)NULL == pv4l2_device) {
+                SAY("ERROR: pv4l2_device is NULL\n");
+                return -EFAULT;
+        }
+        peasycap = (struct easycap *) \
+                container_of(pv4l2_device, struct easycap, v4l2_device);
+}
+#endif /*EASYCAP_NEEDS_V4L2_DEVICE_H*/
+#
+#endif /*EASYCAP_IS_VIDEODEV_CLIENT*/
+/*^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^*/
+/*---------------------------------------------------------------------------*/
+if (memcmp(&peasycap->telltale[0], TELLTALE, strlen(TELLTALE))) {
+        SAY("ERROR: bad peasycap: 0x%08lX\n", (unsigned long int) peasycap);
+        return -EFAULT;
+}
+/*---------------------------------------------------------------------------*/
 
 file->private_data = peasycap;
 
@@ -624,7 +669,7 @@ JOM(4, "starting initialization\n");
 
 if ((struct usb_device *)NULL == peasycap->pusb_device) {
         SAM("ERROR: peasycap->pusb_device is NULL\n");
-        return -EFAULT;
+        return -ENODEV;
 }
 JOM(16, "0x%08lX=peasycap->pusb_device\n", (long int)peasycap->pusb_device);
 
@@ -641,7 +686,7 @@ if ((struct usb_device *)NULL == peasycap->pusb_device) {
 /*---------------------------------------------------------------------------*/
 if ((struct usb_device *)NULL == peasycap->pusb_device) {
         SAM("ERROR: peasycap->pusb_device has become NULL\n");
-        return -EFAULT;
+        return -ENODEV;
 }
 rc = usb_set_interface(peasycap->pusb_device, peasycap->audio_interface, \
                                         peasycap->audio_altsetting_on);
@@ -678,6 +723,10 @@ if (NULL == peasycap) {
         SAY("ERROR:  peasycap is NULL.\n");
         return -EFAULT;
 }
+if (memcmp(&peasycap->telltale[0], TELLTALE, strlen(TELLTALE))) {
+        SAY("ERROR: bad peasycap: 0x%08lX\n", (unsigned long int) peasycap);
+        return -EFAULT;
+}
 if (0 != kill_audio_urbs(peasycap)) {
         SAM("ERROR: kill_audio_urbs() failed\n");
         return -EFAULT;
@@ -722,6 +771,10 @@ if (NULL == peasycap) {
         SAY("ERROR in easysnd_read(): peasycap is NULL\n");
         return -EFAULT;
 }
+if (memcmp(&peasycap->telltale[0], TELLTALE, strlen(TELLTALE))) {
+        SAY("ERROR: bad peasycap: 0x%08lX\n", (unsigned long int) peasycap);
+        return -EFAULT;
+}
 if (NULL == peasycap->pusb_device) {
         SAY("ERROR in easysnd_read(): peasycap->pusb_device is NULL\n");
         return -EFAULT;
@@ -753,6 +806,12 @@ if (0 <= kd && DONGLE_MANY > kd) {
                 mutex_unlock(&easycap_dongle[kd].mutex_audio);
                 return -ERESTARTSYS;
         }
+        if (memcmp(&peasycap->telltale[0], TELLTALE, strlen(TELLTALE))) {
+                SAY("ERROR: bad peasycap: 0x%08lX\n", \
+                                                (unsigned long int) peasycap);
+                mutex_unlock(&easycap_dongle[kd].mutex_audio);
+                return -ERESTARTSYS;
+        }
         if (NULL == peasycap->pusb_device) {
                 SAM("ERROR: peasycap->pusb_device is NULL\n");
                 mutex_unlock(&easycap_dongle[kd].mutex_audio);