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Commit 90a5ad52 authored by Takashi Iwai's avatar Takashi Iwai Committed by Linus Torvalds
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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: default avatarTobin Davis <tdavis@dsl-only.net>
Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 92eed66d

sound/pci/hda/hda_intel.c

+21 −0
Original line number Diff line number Diff line
@@ -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? */