drm/i915: refine qemu south bridge detection

The test for the qemu q35 south bridge added by commit
"39bfcd52 drm/i915: more virtual south bridge detection"
also matches on real hardware.  Having the check for
virtual systems last in the list is not enough to avoid
that ...

Refine the check by additionally verifying the pci
subsystem id to see whenever it *really* is qemu.

[ v2: fix subvendor tyops ]

Reported-and-tested-by: Bjørn Mork <bjorn@mork.no>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Tested-by: Bruno Wolff III <bruno@wolff.to>
Cc: drm-intel-fixes@lists.freedesktop.org
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1453719748-10944-1-git-send-email-kraxel@redhat.com

diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index 706b8eabfaf4940d84a2f290674205b08d9acde8..11d8414edbbea0cb00a2644e9be3b25fdc6b5fd0 100644 (file)
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -501,7 +501,9 @@ void intel_detect_pch(struct drm_device *dev)
                                WARN_ON(!IS_SKYLAKE(dev) &&
                                        !IS_KABYLAKE(dev));
                        } else if ((id == INTEL_PCH_P2X_DEVICE_ID_TYPE) ||
-                                  (id == INTEL_PCH_QEMU_DEVICE_ID_TYPE)) {
+                                  ((id == INTEL_PCH_QEMU_DEVICE_ID_TYPE) &&
+                                   pch->subsystem_vendor == 0x1af4 &&
+                                   pch->subsystem_device == 0x1100)) {
                                dev_priv->pch_type = intel_virt_detect_pch(dev);
                        } else
                                continue;