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[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>
This commit is contained in:
Takashi Iwai 2008-02-22 18:36:22 +01:00 committed by Linus Torvalds
parent 92eed66d5e
commit 90a5ad52bf
1 changed files with 21 additions and 0 deletions
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21
sound/pci/hda/hda_intel.c
View File

@ -275,6 +275,11 @@ enum {
#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 update_pci_byte(struct pci_dev *pci, unsigned int reg,
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 @@ static void azx_init_pci(struct azx *chip)
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 int azx_setup_controller(struct azx *chip, struct azx_dev *azx_dev)
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? */