[PATCH] drm/i915: Remove reserved stolen range ristriction from gen12.5

[Nirmoy Das]

HW spec lifted the requirement for 1st stolen page from
gem12.5 so adjust stolen code.

Signed-off-by: Nirmoy Das <nirmoy.das at intel.com>
---
 drivers/gpu/drm/i915/gem/i915_gem_stolen.c | 20 ++++++++++++++++++--
 drivers/gpu/drm/i915/gt/selftest_reset.c   | 10 +++++++---
 2 files changed, 25 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_stolen.c b/drivers/gpu/drm/i915/gem/i915_gem_stolen.c
index ad6dd7f3259b..254d64ca5f10 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_stolen.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_stolen.c
@@ -63,10 +63,26 @@ int i915_gem_stolen_insert_node(struct drm_i915_private *i915,
 				struct drm_mm_node *node, u64 size,
 				unsigned alignment)
 {
+	/*
+	 * Exclude 128KiB of stolen as this is found to be clobbered
+	 * by the HW on reset.
+	 */
+	u64 start = I915_GEM_STOLEN_BIAS;
+
+	/*
+	 * Lift I915_GEM_STOLEN_BIAS restriction from gen12.5 onwards
+	 * as HW spec explicitly suggested usability of whole stolen
+	 * memory range except the 1st page of stolen which prohibited for
+	 * any platform with display + FBC. Exclude the 1st page for all
+	 * platforms even when no display is present to keep the
+	 * code simple here.
+	 */
+	if (GRAPHICS_VER_FULL(i915) >= IP_VER(12, 50))
+		start = 4096;
+
 	return i915_gem_stolen_insert_node_in_range(i915, node,
 						    size, alignment,
-						    I915_GEM_STOLEN_BIAS,
-						    U64_MAX);
+						    start, U64_MAX);
 }
 
 void i915_gem_stolen_remove_node(struct drm_i915_private *i915,
diff --git a/drivers/gpu/drm/i915/gt/selftest_reset.c b/drivers/gpu/drm/i915/gt/selftest_reset.c
index f40de408cd3a..0b3670c91b72 100644
--- a/drivers/gpu/drm/i915/gt/selftest_reset.c
+++ b/drivers/gpu/drm/i915/gt/selftest_reset.c
@@ -27,6 +27,7 @@ __igt_reset_stolen(struct intel_gt *gt,
 	enum intel_engine_id id;
 	struct igt_spinner spin;
 	long max, count;
+	long reserved = 4096; /* see i915_gem_stolen_insert_node() */
 	void *tmp;
 	u32 *crc;
 	int err;
@@ -48,6 +49,9 @@ __igt_reset_stolen(struct intel_gt *gt,
 		goto err_crc;
 	}
 
+	if (GRAPHICS_VER_FULL(gt->i915) < IP_VER(12, 50))
+		reserved = I915_GEM_STOLEN_BIAS;
+
 	igt_global_reset_lock(gt);
 	wakeref = intel_runtime_pm_get(gt->uncore->rpm);
 
@@ -163,9 +167,9 @@ __igt_reset_stolen(struct intel_gt *gt,
 		pr_info("%s reset clobbered %ld pages of stolen, last clobber at page %ld\n",
 			msg, count, max);
 	}
-	if (max >= I915_GEM_STOLEN_BIAS >> PAGE_SHIFT) {
-		pr_err("%s reset clobbered unreserved area [above %x] of stolen; may cause severe faults\n",
-		       msg, I915_GEM_STOLEN_BIAS);
+	if (max >= reserved >> PAGE_SHIFT) {
+		pr_err("%s reset clobbered unreserved area [above %lx] of stolen; may cause severe faults\n",
+		       msg, reserved);
 		err = -EINVAL;
 	}
 
-- 
2.42.0