ALSA: hda - Check the dead HDMI audio controller by vga-switcheroo

When a discrete-GPU is disabled by the VGA switcheroo, the
corresponding HD-audio controller for HDMI output is also disabled.
Such a dead controller still appears in the PCI device list, but you
can't access properly any longer (even calling pci_read_config_*()
triggers Oops!) which leads the stall of the whole communication of
the driver.

This patch adds a check of graphics controller at the probe time to
see whether it's disabled by vga-switcheroo.  If disabled, skip the
whole initialization of this controller.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=43155

Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/sound/pci/hda/hda_intel.c b/sound/pci/hda/hda_intel.c
index a70d7e5..06a4ad3 100644 (file)
--- a/sound/pci/hda/hda_intel.c
+++ b/sound/pci/hda/hda_intel.c
@@ -53,6 +53,7 @@
 #endif
 #include <sound/core.h>
 #include <sound/initval.h>
+#include <linux/vgaarb.h>
 #include "hda_codec.h"
 
 
@@ -2493,6 +2494,45 @@ static int azx_dev_free(struct snd_device *device)
        return azx_free(device->device_data);
 }
 
+/*
+ * Check of disabled HDMI controller by vga-switcheroo
+ */
+static struct pci_dev __devinit *get_bound_vga(struct pci_dev *pci)
+{
+       struct pci_dev *p;
+
+       /* check only discrete GPU */
+       switch (pci->vendor) {
+       case PCI_VENDOR_ID_ATI:
+       case PCI_VENDOR_ID_AMD:
+       case PCI_VENDOR_ID_NVIDIA:
+               if (pci->devfn == 1) {
+                       p = pci_get_domain_bus_and_slot(pci_domain_nr(pci->bus),
+                                                       pci->bus->number, 0);
+                       if (p) {
+                               if ((p->class >> 8) == PCI_CLASS_DISPLAY_VGA)
+                                       return p;
+                               pci_dev_put(p);
+                       }
+               }
+               break;
+       }
+       return NULL;
+}
+
+static bool __devinit check_hdmi_disabled(struct pci_dev *pci)
+{
+       bool vga_inactive = false;
+       struct pci_dev *p = get_bound_vga(pci);
+
+       if (p) {
+               if (vga_default_device() && p != vga_default_device())
+                       vga_inactive = true;
+               pci_dev_put(p);
+       }
+       return vga_inactive;
+}
+
 /*
  * white/black-listing for position_fix
  */
@@ -2928,6 +2968,12 @@ static int __devinit azx_probe(struct pci_dev *pci,
                return -ENOENT;
        }
 
+       if (check_hdmi_disabled(pci)) {
+               snd_printk(KERN_INFO SFX
+                          "Inactive VGA controller; disabled audio, too\n");
+               goto out;
+       }
+
        err = snd_card_create(index[dev], id[dev], THIS_MODULE, 0, &card);
        if (err < 0) {
                snd_printk(KERN_ERR SFX "Error creating card!\n");
@@ -2984,8 +3030,10 @@ static int __devinit azx_probe(struct pci_dev *pci,
        power_down_all_codecs(chip);
        azx_notifier_register(chip);
 
+ out:
        dev++;
-       return err;
+       return 0;
+
 out_free:
        snd_card_free(card);
        return err;
@@ -2993,7 +3041,9 @@ out_free:
 
 static void __devexit azx_remove(struct pci_dev *pci)
 {
-       snd_card_free(pci_get_drvdata(pci));
+       struct snd_card *card = pci_get_drvdata(pci);
+       if (card)
+               snd_card_free(card);
        pci_set_drvdata(pci, NULL);
 }