drm/i915: Filter pci devices based on PCI_CLASS_DISPLAY_VGA

This fixes hangs on 855-class hardware by avoiding double attachment of the
driver due to the stub second head device having the same pci id as the real
device.

Other DRM drivers probably want this treatment as well, but I'm applying it
just to this one for safety. But we should clean up the drm_pciids.h mess
now so that each driver has its own pci id list header in its own directory.
Lets do that in the next release.

Signed-off-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 9 insertions, 1 deletions

diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
index 96f416afc3f6..3ab1e9cc4692 100644
--- a/drivers/gpu/drm/drm_drv.c
+++ b/drivers/gpu/drm/drm_drv.c
@@ -266,11 +266,19 @@ int drm_init(struct drm_driver *driver)
         for (i = 0; driver->pci_driver.id_table[i].vendor != 0; i++) {
                 pid = (struct pci_device_id *)&driver->pci_driver.id_table[i];
 
+                /* Loop around setting up a DRM device for each PCI device
+                 * matching our ID and device class.  If we had the internal
+                 * function that pci_get_subsys and pci_get_class used, we'd
+                 * be able to just pass pid in instead of doing a two-stage
+                 * thing.
+                 */
                 pdev = NULL;
-                /* pass back in pdev to account for multiple identical cards */
                 while ((pdev =
                         pci_get_subsys(pid->vendor, pid->device, pid->subvendor,
                                        pid->subdevice, pdev)) != NULL) {
+                        if ((pdev->class & pid->class_mask) != pid->class)
+                                continue;
+
                         /* stealth mode requires a manual probe */
                         pci_dev_get(pdev);
                         drm_get_dev(pdev, pid, driver);