[ALSA] HDA - enable snoop on SCH
This patch enables snoop on Intel SCH chipset, eliminating static during
playback.
Signed-off-by: Tobin Davis <tdavis@dsl-only.net>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/sound/pci/hda/hda_intel.c b/sound/pci/hda/hda_intel.c
index 56f8a30..a1098bb 100644
--- a/sound/pci/hda/hda_intel.c
+++ b/sound/pci/hda/hda_intel.c
@@ -275,6 +275,11 @@
#define NVIDIA_HDA_TRANSREG_ADDR 0x4e
#define NVIDIA_HDA_ENABLE_COHBITS 0x0f
+/* Defines for Intel SCH HDA snoop control */
+#define INTEL_SCH_HDA_DEVC 0x78
+#define INTEL_SCH_HDA_DEVC_NOSNOOP (0x1<<11)
+
+
/*
*/
@@ -868,6 +873,8 @@
static void azx_init_pci(struct azx *chip)
{
+ unsigned short snoop;
+
/* Clear bits 0-2 of PCI register TCSEL (at offset 0x44)
* TCSEL == Traffic Class Select Register, which sets PCI express QOS
* Ensuring these bits are 0 clears playback static on some HD Audio
@@ -888,6 +895,19 @@
NVIDIA_HDA_TRANSREG_ADDR,
0x0f, NVIDIA_HDA_ENABLE_COHBITS);
break;
+ case AZX_DRIVER_SCH:
+ pci_read_config_word(chip->pci, INTEL_SCH_HDA_DEVC, &snoop);
+ if (snoop & INTEL_SCH_HDA_DEVC_NOSNOOP) {
+ pci_write_config_word(chip->pci, INTEL_SCH_HDA_DEVC, \
+ snoop & (~INTEL_SCH_HDA_DEVC_NOSNOOP));
+ pci_read_config_word(chip->pci,
+ INTEL_SCH_HDA_DEVC, &snoop);
+ snd_printdd("HDA snoop disabled, enabling ... %s\n",\
+ (snoop & INTEL_SCH_HDA_DEVC_NOSNOOP) \
+ ? "Failed" : "OK");
+ }
+ break;
+
}
}
@@ -1040,6 +1060,7 @@
static unsigned int azx_max_codecs[] __devinitdata = {
[AZX_DRIVER_ICH] = 3,
+ [AZX_DRIVER_SCH] = 3,
[AZX_DRIVER_ATI] = 4,
[AZX_DRIVER_ATIHDMI] = 4,
[AZX_DRIVER_VIA] = 3, /* FIXME: correct? */