patch-2.2.0-pre6 linux/Documentation/sound/VIA-chipset

• Lines: 44
• Date: Thu Jan 7 08:41:55 1999
• Orig file: v2.2.0-pre5/linux/Documentation/sound/VIA-chipset
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.2.0-pre5/linux/Documentation/sound/VIA-chipset linux/Documentation/sound/VIA-chipset
@@ -0,0 +1,43 @@
+Running sound cards on VIA chipsets
+
+o	There are problems with VIA chipsets and sound cards that appear to
+	lock the hardware solidly. Test programs under DOS have verified the
+	problem exists on at least some (but apparently not all) VIA boards
+
+o	VIA have so far failed to bother to answer support mail on the subject
+	so if you are a VIA engineer feeling aggrieved as you read this 
+	document go chase your own people. If there is a workaround please
+	let us know so we can implement it.
+
+
+Certain patterns of ISA DMA access used for most PC sound cards cause the
+VIA chipsets to lock up. From the collected reports this appears to cover a
+wide range of boards. Some also lock up with sound cards under Win* as well.
+
+Linux implements a workaround providing your chipset is PCI and you compiled
+with PCI Quirks enabled. If so you will see a message
+	"Activating ISA DMA bug workarounds"
+
+during booting. If you have a VIA PCI chipset that hangs when you use the
+sound and is not generating this message even with PCI quirks enabled
+please report the information to the linux-kernel list (see REPORTING-BUGS).
+
+If you are one of the tiny number of unfortunates with a 486 ISA/VLB VIA
+chipset board you need to do the following to build a special kernel for
+your board
+
+	edit linux/include/asm-i386/dma.h
+
+change
+
+#define isa_dma_bridge_buggy 	(0)
+
+to
+
+#define isa_dma_bridge_buggy 	(1)
+
+and rebuild a kernel without PCI quirk support.
+
+
+Other than this paticular glitch the VIA [M]VP* chipsets appear to work
+perfectly with Linux.