[PATCH] Fix intel_detect_pch() to work in xen environment.

* [PATCH] Fix intel_detect_pch() to work in xen environment.
@ 2012-12-18 16:49 G.R.
  2012-12-18 16:53 ` Jesse Barnes
  2012-12-18 17:21 ` Ben Widawsky
  0 siblings, 2 replies; 16+ messages in thread
From: G.R. @ 2012-12-18 16:49 UTC (permalink / raw)
  To: intel-gfx; +Cc: Stefano Stabellini, Dong, Eddie, Xu, Dongxiao, Zhang, Xiantao

Hi guys,

In XEN HVM guest, there is always an emulated PIIX3 ISA bridge on slot 01.0.
This shadows the PCH ISA bridge on 1f.0 with the current
intel_detect_pch() implementation.
The issue can be easily solved by looping through all the ISA bridges
until the first match is found, instead of just check against the
first one.

Here I attach the patch I used locally. It's created on Torvalds's git.
Looking forward to your comments.

Thanks,
Timothy

diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index 530db83..3f7e5fb 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -408,9 +408,11 @@ void intel_detect_pch(struct drm_device *dev)
         * underneath. This is a requirement from virtualization team.
         */
        pch = pci_get_class(PCI_CLASS_BRIDGE_ISA << 8, NULL);
-       if (pch) {
+       while (pch) {
+               struct pci_dev * curr = pch;
                if (pch->vendor == PCI_VENDOR_ID_INTEL) {
                        unsigned short id;
+                       unsigned found = 1;
                        id = pch->device & INTEL_PCH_DEVICE_ID_MASK;
                        dev_priv->pch_id = id;

@@ -440,10 +442,20 @@ void intel_detect_pch(struct drm_device *dev)
                                dev_priv->num_pch_pll = 0;
                                DRM_DEBUG_KMS("Found LynxPoint LP PCH\n");
                                WARN_ON(!IS_HASWELL(dev));
+                       } else {
+                               found = 0;
+                       }
+                       if (found) {
+                               BUG_ON(dev_priv->num_pch_pll > I915_NUM_PLLS);
+                               pci_dev_put(pch);
+                               break;
                        }
-                       BUG_ON(dev_priv->num_pch_pll > I915_NUM_PLLS);
                }
-               pci_dev_put(pch);
+               pch = pci_get_class(PCI_CLASS_BRIDGE_ISA << 8, curr);
+               pci_dev_put(curr);
+       }
+       if (!pch) {
+               DRM_DEBUG_KMS("No PCH found?\n");
        }
 }

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