[PATCH] v4l: oopsfix for BTTV on badly behaved PCI chipsets

no_overlay bttv parameter implemented to fix OOPS on some PCI chipsets
(like some VIA) with these behaviors:

1) If pci_quicks does identify the chip as having troubles to
   handle PCI2PCI transfers, no_overlay defaults to 1. The user may force
   it to 0, to reenable (not recommended).

2) For newer chipsets not blacklisted, no_overlay=1 is provided as a
   workaround until PCI chipset included on /drivers/pci/quirks.c

Thanks to Bodo Eggert <7eggert@gmx.de>
Signed-off-by: Michael Krufky <mkrufky@m1k.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@brturbo.com.br>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

Documentation/video4linux/bttv/Insmod-options

@@ -44,6 +44,9 @@ bttv.o
 				push used by bttv.  bttv will disable overlay
 				by default on this hardware to avoid crashes.
 				With this insmod option you can override this.
+		no_overlay=1	Disable overlay. It should be used by broken
+				hardware that doesn't support PCI2PCI direct
+				transfers.
 		automute=0/1	Automatically mutes the sound if there is
 				no TV signal, on by default.  You might try
 				to disable this if you have bad input signal

drivers/media/video/bttv-cards.c

@@ -95,7 +95,7 @@ static int __devinit pvr_boot(struct bttv *btv);
 static unsigned int triton1=0;
 static unsigned int vsfx=0;
 static unsigned int latency = UNSET;
-static unsigned int no_overlay=-1;
+int no_overlay=-1;
 
 static unsigned int card[BTTV_MAX]   = { [ 0 ... (BTTV_MAX-1) ] = UNSET };
 static unsigned int pll[BTTV_MAX]    = { [ 0 ... (BTTV_MAX-1) ] = UNSET };
@@ -4296,9 +4296,11 @@ void __devinit bttv_check_chipset(void)
 		printk(KERN_INFO "bttv: Host bridge needs VSFX enabled.\n");
 	if (pcipci_fail) {
 		printk(KERN_WARNING "bttv: BT848 and your chipset may not work together.\n");
-		if (UNSET == no_overlay) {
-			printk(KERN_WARNING "bttv: going to disable overlay.\n");
+		if (!no_overlay) {
+			printk(KERN_WARNING "bttv: overlay will be disabled.\n");
 			no_overlay = 1;
+		} else {
+			printk(KERN_WARNING "bttv: overlay forced. Use this option at your own risk.\n");
 		}
 	}
 	if (UNSET != latency)

drivers/media/video/bttv-driver.c

 /*
-    $Id: bttv-driver.c,v 1.45 2005/07/20 19:43:24 mkrufky Exp $
+    $Id: bttv-driver.c,v 1.52 2005/08/04 00:55:16 mchehab Exp $
 
     bttv - Bt848 frame grabber driver
 
@@ -80,6 +80,7 @@ static unsigned int irq_iswitch = 0;
 static unsigned int uv_ratio    = 50;
 static unsigned int full_luma_range = 0;
 static unsigned int coring      = 0;
+extern int no_overlay;
 
 /* API features (turn on/off stuff for testing) */
 static unsigned int v4l2        = 1;
@@ -2151,6 +2152,10 @@ static int bttv_s_fmt(struct bttv_fh *fh, struct bttv *btv,
 		return 0;
 	}
 	case V4L2_BUF_TYPE_VIDEO_OVERLAY:
+		if (no_overlay > 0) {
+			printk ("V4L2_BUF_TYPE_VIDEO_OVERLAY: no_overlay\n");
+			return -EINVAL;
+		}
 		return setup_window(fh, btv, &f->fmt.win, 1);
 	case V4L2_BUF_TYPE_VBI_CAPTURE:
 		retval = bttv_switch_type(fh,f->type);
@@ -2224,9 +2229,11 @@ static int bttv_do_ioctl(struct inode *inode, struct file *file,
 			/* others */
 			cap->type = VID_TYPE_CAPTURE|
 				VID_TYPE_TUNER|
-				VID_TYPE_OVERLAY|
 				VID_TYPE_CLIPPING|
 				VID_TYPE_SCALES;
+			if (no_overlay <= 0)
+				cap->type |= VID_TYPE_OVERLAY;
+
 			cap->maxwidth  = bttv_tvnorms[btv->tvnorm].swidth;
 			cap->maxheight = bttv_tvnorms[btv->tvnorm].sheight;
 			cap->minwidth  = 48;
@@ -2302,6 +2309,11 @@ static int bttv_do_ioctl(struct inode *inode, struct file *file,
 		struct video_window *win = arg;
 		struct v4l2_window w2;
 
+		if (no_overlay > 0) {
+			printk ("VIDIOCSWIN: no_overlay\n");
+			return -EINVAL;
+		}
+
 		w2.field = V4L2_FIELD_ANY;
 		w2.w.left    = win->x;
 		w2.w.top     = win->y;
@@ -2577,10 +2589,12 @@ static int bttv_do_ioctl(struct inode *inode, struct file *file,
 		cap->version = BTTV_VERSION_CODE;
 		cap->capabilities =
 			V4L2_CAP_VIDEO_CAPTURE |
-			V4L2_CAP_VIDEO_OVERLAY |
 			V4L2_CAP_VBI_CAPTURE |
 			V4L2_CAP_READWRITE |
 			V4L2_CAP_STREAMING;
+		if (no_overlay <= 0)
+			cap->capabilities |= V4L2_CAP_VIDEO_OVERLAY;
+
 		if (bttv_tvcards[btv->c.type].tuner != UNSET &&
 		    bttv_tvcards[btv->c.type].tuner != TUNER_ABSENT)
 			cap->capabilities |= V4L2_CAP_TUNER;
@@ -3076,7 +3090,7 @@ static struct file_operations bttv_fops =
 static struct video_device bttv_video_template =
 {
 	.name     = "UNSET",
-	.type     = VID_TYPE_CAPTURE|VID_TYPE_TUNER|VID_TYPE_OVERLAY|
+	.type     = VID_TYPE_CAPTURE|VID_TYPE_TUNER|
 	            VID_TYPE_CLIPPING|VID_TYPE_SCALES,
 	.hardware = VID_HARDWARE_BT848,
 	.fops     = &bttv_fops,
@@ -3756,6 +3770,12 @@ static void bttv_unregister_video(struct bttv *btv)
 /* register video4linux devices */
 static int __devinit bttv_register_video(struct bttv *btv)
 {
+	if (no_overlay <= 0) {
+		bttv_video_template.type |= VID_TYPE_OVERLAY;
+	} else {
+		printk("bttv: Overlay support disabled.\n");
+	}
+
 	/* video */
 	btv->video_dev = vdev_init(btv, &bttv_video_template, "video");
         if (NULL == btv->video_dev)