On Wed, 19 Dec 2012 00:49:28 +0800
"G.R." <firemeteor at users.sourceforge.net> wrote:
> 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");
> }
> }
>
I'd like to see a comment about this being for Xen in here, and I
wonder if there are other places where we might have to worry about the
Xen implementation. In that case, setting a flag in dev_priv when we
don't find the PCH where we expect would be a good idea too.
Ack on the general idea though; I'd like us to be able to run under Xen
without modification.
Jesse
--
Jesse Barnes, Intel Open Source Technology Center
