[PATCH] Fix Oops in MXB driver (v4l2 subsystem)

This fixes a NULL pointer dereference Oops in my "Multimedia eXtension
Board" driver. 

The tda9840 i2c driver dereferences the argument pointer, but the MXB
driver is supplying a NULL pointer for one of the commands.  The patch
makes this one command behave like the others, ie.  it expects an int
argument.

Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/drivers/media/video/mxb.c b/drivers/media/video/mxb.c
index a76571d..70bf1f1 100644
--- a/drivers/media/video/mxb.c
+++ b/drivers/media/video/mxb.c
@@ -731,7 +731,7 @@
 		t->signal = 0xffff;
 		t->afc = 0;		
 
-		byte = mxb->tda9840->driver->command(mxb->tda9840,TDA9840_DETECT, NULL);
+		mxb->tda9840->driver->command(mxb->tda9840,TDA9840_DETECT, &byte);
 		t->audmode = mxb->cur_mode;
 		
 		if( byte < 0 ) {
diff --git a/drivers/media/video/tda9840.c b/drivers/media/video/tda9840.c
index 8de20ad..b5177c6 100644
--- a/drivers/media/video/tda9840.c
+++ b/drivers/media/video/tda9840.c
@@ -117,7 +117,8 @@
 			dprintk("i2c_smbus_write_byte() failed, ret:%d\n", result);
 		break;
 
-	case TDA9840_DETECT:
+	case TDA9840_DETECT: {
+		int *ret = (int *)arg;
 
 		byte = i2c_smbus_read_byte_data(client, STEREO_ADJUST);
 		if (byte == -1) {
@@ -131,8 +132,10 @@
 		}
 
 		dprintk("TDA9840_DETECT: byte: 0x%02x\n", byte);
-		return ((byte & 0x60) >> 5);
-
+		*ret = ((byte & 0x60) >> 5);
+		result = 0;
+		break;
+	}
 	case TDA9840_TEST:
 		dprintk("TDA9840_TEST: 0x%02x\n", byte);