drm/i915: refine qemu south bridge detection

commit f2e305108faba0c85eb4ba4066599decb675117e upstream.

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
(cherry picked from commit 1e859111c128265f8d62b39ff322e42b1ddb5a20)
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index a3c482e59930ad99454c42ff290560e6a5d56082..a6ad938f44a68f736e30921ad04094a73cab0668 100644 (file)
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -532,7 +532,9 @@ void intel_detect_pch(struct drm_device *dev)
                                DRM_DEBUG_KMS("Found SunrisePoint LP PCH\n");
                                WARN_ON(!IS_SKYLAKE(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;