ALSA: hda_intel: enable snoop for nvidia HDA controller

Enable the snoop for nvidia hda controller to avoid data coherence issue.
Signed-off-by: Peer Chen <peerchen@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/pci/hda/hda_intel.c

@@ -278,6 +278,9 @@ enum {
 /* Defines for Nvidia HDA support */
 #define NVIDIA_HDA_TRANSREG_ADDR      0x4e
 #define NVIDIA_HDA_ENABLE_COHBITS     0x0f
+#define NVIDIA_HDA_ISTRM_COH          0x4d
+#define NVIDIA_HDA_OSTRM_COH          0x4c
+#define NVIDIA_HDA_ENABLE_COHBIT      0x01
 
 /* Defines for Intel SCH HDA snoop control */
 #define INTEL_SCH_HDA_DEVC      0x78
@@ -900,6 +903,12 @@ static void azx_init_pci(struct azx *chip)
 		update_pci_byte(chip->pci,
 				NVIDIA_HDA_TRANSREG_ADDR,
 				0x0f, NVIDIA_HDA_ENABLE_COHBITS);
+		update_pci_byte(chip->pci,
+				NVIDIA_HDA_ISTRM_COH,
+				0x01, NVIDIA_HDA_ENABLE_COHBIT);
+		update_pci_byte(chip->pci,
+				NVIDIA_HDA_OSTRM_COH,
+				0x01, NVIDIA_HDA_ENABLE_COHBIT);
 		break;
 	case AZX_DRIVER_SCH:
 		pci_read_config_word(chip->pci, INTEL_SCH_HDA_DEVC, &snoop);