drm/i915: Try to guess PCH type even without ISA bridge

Some vmm like hyperv and crosvm don't supply any ISA bridge to their guest,
when igd passthrough is equipped on these vmm, guest i915 display may
couldn't work as guest i915 detects PCH_NONE pch type.

When i915 runs as guest, this patch guess pch type through gpu type even
without ISA bridge.

v2: Fix CI warning
v3: Add HAS_DISPLAY()= true condition beforce guessing virt pch, then
    refactori.
v4: Fix CI warning

Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Co-developed-by: Xiong Zhang <xiong.y.zhang@intel.com>
Signed-off-by: Xiong Zhang <xiong.y.zhang@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210114005819.4290-1-xiong.y.zhang@intel.com

1 files changed, 22 insertions, 17 deletions

diff --git a/drivers/gpu/drm/i915/intel_pch.c b/drivers/gpu/drm/i915/intel_pch.c
index f31c0dabd0cc..ecaf314d60b6 100644
--- a/drivers/gpu/drm/i915/intel_pch.c
+++ b/drivers/gpu/drm/i915/intel_pch.c
@@ -143,8 +143,9 @@ static bool intel_is_virt_pch(unsigned short id,
 		 sdevice == PCI_SUBDEVICE_ID_QEMU));
 }
 
-static unsigned short
-intel_virt_detect_pch(const struct drm_i915_private *dev_priv)
+static void
+intel_virt_detect_pch(const struct drm_i915_private *dev_priv,
+		      unsigned short *pch_id, enum intel_pch *pch_type)
 {
 	unsigned short id = 0;
 
@@ -181,12 +182,21 @@ intel_virt_detect_pch(const struct drm_i915_private *dev_priv)
 	else
 		drm_dbg_kms(&dev_priv->drm, "Assuming no PCH\n");
 
-	return id;
+	*pch_type = intel_pch_type(dev_priv, id);
+
+	/* Sanity check virtual PCH id */
+	if (drm_WARN_ON(&dev_priv->drm,
+			id && *pch_type == PCH_NONE))
+		id = 0;
+
+	*pch_id = id;
 }
 
 void intel_detect_pch(struct drm_i915_private *dev_priv)
 {
 	struct pci_dev *pch = NULL;
+	unsigned short id;
+	enum intel_pch pch_type;
 
 	/* DG1 has south engine display on the same PCI device */
 	if (IS_DG1(dev_priv)) {
@@ -206,9 +216,6 @@ void intel_detect_pch(struct drm_i915_private *dev_priv)
 	 * of only checking the first one.
 	 */
 	while ((pch = pci_get_class(PCI_CLASS_BRIDGE_ISA << 8, pch))) {
-		unsigned short id;
-		enum intel_pch pch_type;
-
 		if (pch->vendor != PCI_VENDOR_ID_INTEL)
 			continue;
 
@@ -221,14 +228,7 @@ void intel_detect_pch(struct drm_i915_private *dev_priv)
 			break;
 		} else if (intel_is_virt_pch(id, pch->subsystem_vendor,
 					     pch->subsystem_device)) {
-			id = intel_virt_detect_pch(dev_priv);
-			pch_type = intel_pch_type(dev_priv, id);
-
-			/* Sanity check virtual PCH id */
-			if (drm_WARN_ON(&dev_priv->drm,
-					id && pch_type == PCH_NONE))
-				id = 0;
-
+			intel_virt_detect_pch(dev_priv, &id, &pch_type);
 			dev_priv->pch_type = pch_type;
 			dev_priv->pch_id = id;
 			break;
@@ -244,10 +244,15 @@ void intel_detect_pch(struct drm_i915_private *dev_priv)
 			    "Display disabled, reverting to NOP PCH\n");
 		dev_priv->pch_type = PCH_NOP;
 		dev_priv->pch_id = 0;
+	} else if (!pch) {
+		if (run_as_guest() && HAS_DISPLAY(dev_priv)) {
+			intel_virt_detect_pch(dev_priv, &id, &pch_type);
+			dev_priv->pch_type = pch_type;
+			dev_priv->pch_id = id;
+		} else {
+			drm_dbg_kms(&dev_priv->drm, "No PCH found.\n");
+		}
 	}
 
-	if (!pch)
-		drm_dbg_kms(&dev_priv->drm, "No PCH found.\n");
-
 	pci_dev_put(pch);
 }