ALSA: hda - Enable snoop bit for AMD controllers

BugLink: http://bugs.launchpad.net/bugs/741825

AMD Hudson controllers give noisy outputs when the buffer data is
rewritten on the fly as PulseAudio does.  This seems fixed by the
snoop bit enabled just like ATI chipset.

Also, disable 64bit DMA as now, to be sure.
We can revisit this later.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
(cherry picked from commit 20c304ed84e05a91b2acae36d428d621d3c1d1c6)
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>

diff --git a/sound/pci/hda/hda_intel.c b/sound/pci/hda/hda_intel.c
index 2b287fb..5fd012b 100644 (file)
--- a/sound/pci/hda/hda_intel.c
+++ b/sound/pci/hda/hda_intel.c
@@ -1088,7 +1088,13 @@ static void azx_init_pci(struct azx *chip)
                                ? "Failed" : "OK");
                }
                break;
-
+       default:
+               /* AMD Hudson needs the similar snoop, as it seems... */
+               if (chip->pci->vendor == PCI_VENDOR_ID_AMD)
+                       update_pci_byte(chip->pci,
+                               ATI_SB450_HDAUDIO_MISC_CNTR2_ADDR,
+                               0x07, ATI_SB450_HDAUDIO_ENABLE_SNOOP);
+               break;
         }
 }
 
@@ -2565,6 +2571,13 @@ static int __devinit azx_create(struct snd_card *card, struct pci_dev *pci,
                                gcap &= ~ICH6_GCAP_64OK;
                        pci_dev_put(p_smbus);
                }
+       } else {
+               /* FIXME: not sure whether this is really needed, but
+                * Hudson isn't stable enough for allowing everything...
+                * let's check later again.
+                */
+               if (chip->pci->vendor == PCI_VENDOR_ID_AMD)
+                       gcap &= ~ICH6_GCAP_64OK;
        }
 
        /* disable 64bit DMA address for Teradici */