drm/i915: Fix MTL initial plane readout

MTL stolen memory looks more like local memory, so use the
(now fixed) lmem path when doing the initial plane readout.
Reviewed-by: Uma Shankar <uma.shankar@intel.com>
Tested-by: Paz Zcharya <pazz@chromium.org>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240202224340.30647-10-ville.syrjala@linux.intel.com

drivers/gpu/drm/i915/display/intel_plane_initial.c

@@ -59,7 +59,7 @@ initial_plane_vma(struct drm_i915_private *i915,
 		return NULL;
 
 	base = round_down(plane_config->base, I915_GTT_MIN_ALIGNMENT);
-	if (IS_DGFX(i915)) {
+	if (IS_DGFX(i915) || HAS_LMEMBAR_SMEM_STOLEN(i915)) {
 		gen8_pte_t __iomem *gte = to_gt(i915)->ggtt->gsm;
 		gen8_pte_t pte;
 
@@ -73,11 +73,20 @@ initial_plane_vma(struct drm_i915_private *i915,
 		}
 
 		phys_base = pte & GEN12_GGTT_PTE_ADDR_MASK;
+
+		if (IS_DGFX(i915))
 			mem = i915->mm.regions[INTEL_REGION_LMEM_0];
+		else
+			mem = i915->mm.stolen_region;
+		if (!mem) {
+			drm_dbg_kms(&i915->drm,
+				    "Initial plane memory region not initialized\n");
+			return NULL;
+		}
 
 		/*
-		 * We don't currently expect this to ever be placed in the
-		 * stolen portion.
+		 * On lmem we don't currently expect this to
+		 * ever be placed in the stolen portion.
 		 */
 		if (phys_base < mem->region.start || phys_base > mem->region.end) {
 			drm_err(&i915->drm,
@@ -94,10 +103,12 @@ initial_plane_vma(struct drm_i915_private *i915,
 	} else {
 		phys_base = base;
 		mem = i915->mm.stolen_region;
-	}
-
-	if (!mem)
+		if (!mem) {
+			drm_dbg_kms(&i915->drm,
+				    "Initial plane memory region not initialized\n");
 			return NULL;
+		}
+	}
 
 	size = round_up(plane_config->base + plane_config->size,
 			mem->min_page_size);