[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>

1 files changed, 5 insertions, 3 deletions

diff --git a/drivers/media/video/bttv-cards.c b/drivers/media/video/bttv-cards.c
index 6c52fd0bb7df..a97b9b958ed6 100644
--- a/drivers/media/video/bttv-cards.c
+++ b/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)