linux-kernel - [PATCH] drm/i915/display: Check GGTT to determine phys

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Message-ID: <20231130161651.1836047-1-pazz@chromium.org>
Date:   Thu, 30 Nov 2023 16:16:37 +0000
From:   Paz Zcharya <pazz@...omium.org>
To:     Andrzej Hajda <andrzej.hajda@...el.com>,
        Tvrtko Ursulin <tvrtko.ursulin@...el.com>
Cc:     Ville Syrjälä 
        <ville.syrjala@...ux.intel.com>, matthew.auld@...el.com,
        intel-gfx@...ts.freedesktop.org,
        Drew Davenport <ddavenport@...omium.org>,
        Rodrigo Vivi <rodrigo.vivi@...el.com>,
        Nirmoy Das <nirmoy.das@...el.com>,
        Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
        Jouni Högander <jouni.hogander@...el.com>,
        Paz Zcharya <pazz@...omium.org>,
        Subrata Banik <subratabanik@...gle.com>,
        dri-devel@...ts.freedesktop.org,
        Manasi Navare <navaremanasi@...omium.org>,
        Jani Nikula <jani.nikula@...ux.intel.com>,
        Sean Paul <seanpaul@...omium.org>,
        Daniel Vetter <daniel@...ll.ch>,
        Marcin Wojtas <mwojtas@...omium.org>,
        linux-kernel@...r.kernel.org, David Airlie <airlied@...il.com>,
        Tvrtko Ursulin <tvrtko.ursulin@...ux.intel.com>
Subject: [PATCH] drm/i915/display: Check GGTT to determine phys_base

There was an assumption that for iGPU there should be a 1:1 mapping
of GGTT to physical address pointing to actual framebuffer.
This assumption is not valid anymore for MTL.
Fix that by checking GGTT to determine the phys address.

The following algorithm for phys_base should be valid for all platforms:
1. Find pte
2. if(IS_DGFX(i915) && pte & GEN12_GGTT_PTE_LM) mem =
i915->mm.regions[INTEL_REGION_LMEM_0] else mem = i915->mm.stolen_region
3. phys_base = (pte & I915_GTT_PAGE_MASK) - mem->region.start;

- On older platforms, stolen_region points to system memory, starting at 0
- on DG2, it uses lmem region which starts at 0 as well
- on MTL, stolen_region points to stolen-local which starts at 0x800000

Signed-off-by: Paz Zcharya <pazz@...omium.org>
---

 .../drm/i915/display/intel_plane_initial.c    | 45 +++++++++----------
 1 file changed, 22 insertions(+), 23 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_plane_initial.c b/drivers/gpu/drm/i915/display/intel_plane_initial.c
index a55c09cbd0e4..c4bf02ea966c 100644
--- a/drivers/gpu/drm/i915/display/intel_plane_initial.c
+++ b/drivers/gpu/drm/i915/display/intel_plane_initial.c
@@ -51,6 +51,8 @@ initial_plane_vma(struct drm_i915_private *i915,
 	struct intel_memory_region *mem;
 	struct drm_i915_gem_object *obj;
 	struct i915_vma *vma;
+	gen8_pte_t __iomem *gte = to_gt(i915)->ggtt->gsm;
+	gen8_pte_t pte;
 	resource_size_t phys_base;
 	u32 base, size;
 	u64 pinctl;
@@ -59,44 +61,41 @@ initial_plane_vma(struct drm_i915_private *i915,
 		return NULL;
 
 	base = round_down(plane_config->base, I915_GTT_MIN_ALIGNMENT);
-	if (IS_DGFX(i915)) {
-		gen8_pte_t __iomem *gte = to_gt(i915)->ggtt->gsm;
-		gen8_pte_t pte;
+	gte += base / I915_GTT_PAGE_SIZE;
 
-		gte += base / I915_GTT_PAGE_SIZE;
+	pte = ioread64(gte);
 
-		pte = ioread64(gte);
+	if (IS_DGFX(i915)) {
 		if (!(pte & GEN12_GGTT_PTE_LM)) {
 			drm_err(&i915->drm,
 				"Initial plane programming missing PTE_LM bit\n");
 			return NULL;
 		}
-
-		phys_base = pte & I915_GTT_PAGE_MASK;
 		mem = i915->mm.regions[INTEL_REGION_LMEM_0];
-
-		/*
-		 * We don't currently expect this to ever be placed in the
-		 * stolen portion.
-		 */
-		if (phys_base >= resource_size(&mem->region)) {
-			drm_err(&i915->drm,
-				"Initial plane programming using invalid range, phys_base=%pa\n",
-				&phys_base);
-			return NULL;
-		}
-
-		drm_dbg(&i915->drm,
-			"Using phys_base=%pa, based on initial plane programming\n",
-			&phys_base);
 	} else {
-		phys_base = base;
 		mem = i915->mm.stolen_region;
 	}
 
+	phys_base = (pte & I915_GTT_PAGE_MASK) - mem->region.start;
+
 	if (!mem)
 		return NULL;
 
+	/*
+	 * We don't currently expect this to ever be placed in the
+	 * stolen portion.
+	 */
+	if (phys_base >= resource_size(&mem->region)) {
+		drm_err(&i915->drm,
+			"Initial plane programming using invalid range, phys_base=%pa\n",
+			&phys_base);
+		return NULL;
+	}
+
+	drm_dbg(&i915->drm,
+		"Using phys_base=%pa, based on initial plane programming\n",
+		&phys_base);
+
 	size = round_up(plane_config->base + plane_config->size,
 			mem->min_page_size);
 	size -= base;
-- 
2.43.0.rc1.413.gea7ed67945-goog