From 6205cf5a3ac48a38a00cc4e1b8eaa3f13f6a6661 Mon Sep 17 00:00:00 2001
From: Deanna Phillips <deanna@cvs.openbsd.org>
Date: Sun, 28 Oct 2007 21:32:52 +0000
Subject: Enable pcie snoop for SB600 and MCP51.  Fixes a variety of noise,
 looping and distortion problems.  This is a temporary solution until we get
 something like the BUS_DMA_NOCACHE flag to bus_dmamem_map(9), which came with
 the driver when ported from NetBSD but means nothing here.  It's likely that
 other NVIDIA and ATI chipsets will need this, but I'd rather have some
 testers before adding them in.

From ariff@freebsd, ok dlg.
---
 sys/dev/pci/azalia.c | 46 +++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 45 insertions(+), 1 deletion(-)

diff --git a/sys/dev/pci/azalia.c b/sys/dev/pci/azalia.c
index 7bea09e9586..0dab65524e4 100644
--- a/sys/dev/pci/azalia.c
+++ b/sys/dev/pci/azalia.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: azalia.c,v 1.37 2007/10/26 02:17:23 deanna Exp $	*/
+/*	$OpenBSD: azalia.c,v 1.38 2007/10/28 21:32:51 deanna Exp $	*/
 /*	$NetBSD: azalia.c,v 1.20 2006/05/07 08:31:44 kent Exp $	*/
 
 /*-
@@ -216,6 +216,8 @@ typedef struct azalia_t {
 
 
 /* prototypes */
+uint8_t azalia_pci_read(pci_chipset_tag_t, pcitag_t, int);
+void	azalia_pci_write(pci_chipset_tag_t, pcitag_t, int, uint8_t);
 int	azalia_pci_match(struct device *, void *, void *);
 void	azalia_pci_attach(struct device *, struct device *, void *);
 int	azalia_pci_activate(struct device *, enum devact);
@@ -358,6 +360,31 @@ static const char *pin_chass[4] = {
 #define PCIID_ALI_M5461		PCI_ID_CODE0(ALI, M5461)
 #define PCIID_VIATECH_HDA	PCI_ID_CODE0(VIATECH, HDA)
 
+#define ATI_PCIE_SNOOP_REG		0x42
+#define ATI_PCIE_SNOOP_MASK		0xf8
+#define ATI_PCIE_SNOOP_ENABLE		0x02
+#define NVIDIA_PCIE_SNOOP_REG		0x4e
+#define NVIDIA_PCIE_SNOOP_MASK		0xf0
+#define NVIDIA_PCIE_SNOOP_ENABLE	0x0f
+
+uint8_t
+azalia_pci_read(pci_chipset_tag_t pc, pcitag_t pa, int reg)
+{
+	return (pci_conf_read(pc, pa, (reg & ~0x03)) >>
+	    ((reg & 0x03) * 8) & 0xff);
+}
+
+void
+azalia_pci_write(pci_chipset_tag_t pc, pcitag_t pa, int reg, uint8_t val)
+{
+	pcireg_t pcival;
+
+	pcival = pci_conf_read(pc, pa, (reg & ~0x03));
+	pcival &= ~(0xff << ((reg & 0x03) * 8));
+	pcival |= (val << ((reg & 0x03) * 8));
+	pci_conf_write(pc, pa, (reg & ~0x03), pcival);
+}
+
 int
 azalia_pci_match(struct device *parent, void *match, void *aux)
 {
@@ -378,6 +405,7 @@ azalia_pci_attach(struct device *parent, struct device *self, void *aux)
 	pcireg_t v;
 	pci_intr_handle_t ih;
 	const char *intrrupt_str;
+	uint8_t reg;
 
 	sc = (azalia_t*)self;
 	pa = aux;
@@ -399,6 +427,22 @@ azalia_pci_attach(struct device *parent, struct device *self, void *aux)
 
 	v = pci_conf_read(pa->pa_pc, pa->pa_tag, 0x44);
 	pci_conf_write(pa->pa_pc, pa->pa_tag, 0x44, v & (~0x7));
+ 
+	/* enable PCIe snoop */
+	switch (PCI_PRODUCT(pa->pa_id)) {
+	case PCI_PRODUCT_ATI_IXP_HDA_600:
+		reg = azalia_pci_read(pa->pa_pc, pa->pa_tag, ATI_PCIE_SNOOP_REG);
+		reg &= ATI_PCIE_SNOOP_MASK;
+		reg |= ATI_PCIE_SNOOP_ENABLE;
+		azalia_pci_write(pa->pa_pc, pa->pa_tag, ATI_PCIE_SNOOP_REG, reg);
+		break;
+	case PCI_PRODUCT_NVIDIA_MCP51_HDA:
+		reg = azalia_pci_read(pa->pa_pc, pa->pa_tag, NVIDIA_PCIE_SNOOP_REG);
+		reg &= NVIDIA_PCIE_SNOOP_MASK;
+		reg |= NVIDIA_PCIE_SNOOP_ENABLE;
+		azalia_pci_write(pa->pa_pc, pa->pa_tag, NVIDIA_PCIE_SNOOP_REG, reg);
+		break;
+	}
 
 	/* interrupt */
 	if (pci_intr_map(pa, &ih)) {
-- 
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