From 90a5ad52bf2ce54aa7153735dc4488f00c050e54 Mon Sep 17 00:00:00 2001 From: Takashi Iwai Date: Fri, 22 Feb 2008 18:36:22 +0100 Subject: [PATCH] [ALSA] HDA - enable snoop on SCH This patch enables snoop on Intel SCH chipset, eliminating static during playback. Signed-off-by: Tobin Davis Signed-off-by: Takashi Iwai Signed-off-by: Linus Torvalds --- sound/pci/hda/hda_intel.c | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) diff --git a/sound/pci/hda/hda_intel.c b/sound/pci/hda/hda_intel.c index 56f8a305075..a1098bb875d 100644 --- a/sound/pci/hda/hda_intel.c +++ b/sound/pci/hda/hda_intel.c @@ -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? */ -- 2.41.1