sound: oxygen: fix for PI7C9X110 compatibility

If the card is used with a Pericom PI7C9X110 PCI-E/PCI bridge,
reconfigure the latter's PCI buffering to fix an unknown problem.

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 23 insertions, 0 deletions

diff --git a/sound/pci/oxygen/oxygen_lib.c b/sound/pci/oxygen/oxygen_lib.c
index c9f271419eb8..9c5e6450eebb 100644
--- a/sound/pci/oxygen/oxygen_lib.c
+++ b/sound/pci/oxygen/oxygen_lib.c
@@ -307,6 +307,28 @@ static void oxygen_restore_eeprom(struct oxygen *chip,
         }
 }
 
+static void pci_bridge_magic(void)
+{
+        struct pci_dev *pci = NULL;
+        u32 tmp;
+
+        for (;;) {
+                /* If there is any Pericom PI7C9X110 PCI-E/PCI bridge ... */
+                pci = pci_get_device(0x12d8, 0xe110, pci);
+                if (!pci)
+                        break;
+                /*
+                 * ... configure its secondary internal arbiter to park to
+                 * the secondary port, instead of to the last master.
+                 */
+                if (!pci_read_config_dword(pci, 0x40, &tmp)) {
+                        tmp |= 1;
+                        pci_write_config_dword(pci, 0x40, tmp);
+                }
+                /* Why?  Try asking C-Media. */
+        }
+}
+
 static void oxygen_init(struct oxygen *chip)
 {
         unsigned int i;
@@ -585,6 +607,7 @@ int oxygen_pci_probe(struct pci_dev *pci, int index, char *id,
         snd_card_set_dev(card, &pci->dev);
         card->private_free = oxygen_card_free;
 
+        pci_bridge_magic();
         oxygen_init(chip);
         chip->model.init(chip);