[Intel-gfx] [PATCH 3/8] drm/i915/guc: Extend the GEN9 WOPCM HW restrictions to early CNL

[Michał Winiarski]

We imposed additional restrictions to GEN9 WOPCM partitioning. However,
we ignored early steppings of CNL, to which those restrictions also
apply. Let's also tweak the logic a bit by having separate helpers for
returning extra size needed for the restriction to be satisfied, and
handle the results in the caller.

References: 6b0478fb722a ("drm/i915: Implement dynamic GuC WOPCM offset and size calculation")
Signed-off-by: Michał Winiarski <michal.winiarski at intel.com>
Cc: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Jackie Li <yaodong.li at intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
Cc: Michal Wajdeczko <michal.wajdeczko at intel.com>
---
 drivers/gpu/drm/i915/intel_wopcm.c | 63 ++++++++++++++++++++++----------------
 1 file changed, 37 insertions(+), 26 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_wopcm.c b/drivers/gpu/drm/i915/intel_wopcm.c
index 42876f8890e7..50854a6b9493 100644
--- a/drivers/gpu/drm/i915/intel_wopcm.c
+++ b/drivers/gpu/drm/i915/intel_wopcm.c
@@ -84,58 +84,69 @@ static inline u32 context_reserved_size(struct drm_i915_private *i915)
 		return 0;
 }
 
-static inline int gen9_check_dword_gap(u32 guc_wopcm_base, u32 guc_wopcm_size)
+static u32
+gen9_size_for_dword_gap_restriction(u32 guc_wopcm_base, u32 guc_wopcm_size)
 {
-	u32 offset;
+	s32 additional_size;
 
 	/*
 	 * GuC WOPCM size shall be at least a dword larger than the offset from
 	 * WOPCM base (GuC WOPCM offset from WOPCM base + GEN9_GUC_WOPCM_OFFSET)
 	 * due to hardware limitation on Gen9.
 	 */
-	offset = guc_wopcm_base + GEN9_GUC_WOPCM_OFFSET;
-	if (offset > guc_wopcm_size ||
-	    (guc_wopcm_size - offset) < sizeof(u32)) {
-		DRM_ERROR("GuC WOPCM size %uKiB is too small. %uKiB needed.\n",
-			  guc_wopcm_size / 1024,
-			  (u32)(offset + sizeof(u32)) / 1024);
-		return -E2BIG;
-	}
+	additional_size = guc_wopcm_base + GEN9_GUC_WOPCM_OFFSET +
+			  sizeof(u32) - guc_wopcm_size;
 
-	return 0;
+	if (additional_size <= 0)
+		return 0;
+
+	return additional_size;
 }
 
-static inline int gen9_check_huc_fw_fits(u32 guc_wopcm_size, u32 huc_fw_size)
+static u32
+gen9_size_for_huc_restriction(u32 guc_wopcm_size, u32 huc_fw_size)
 {
+	s32 additional_size;
+
 	/*
 	 * On Gen9 & CNL A0, hardware requires the total available GuC WOPCM
 	 * size to be larger than or equal to HuC firmware size. Otherwise,
 	 * firmware uploading would fail.
 	 */
-	if (huc_fw_size > guc_wopcm_size - GUC_WOPCM_RESERVED) {
-		DRM_ERROR("HuC FW (%uKiB) won't fit in GuC WOPCM (%uKiB).\n",
-			  huc_fw_size / 1024,
-			  (guc_wopcm_size - GUC_WOPCM_RESERVED) / 1024);
-		return -E2BIG;
-	}
+	additional_size = huc_fw_size - (guc_wopcm_size - GUC_WOPCM_RESERVED);
 
-	return 0;
+	if (additional_size <= 0)
+		return 0;
+
+	return additional_size;
 }
 
 static inline int check_hw_restriction(struct drm_i915_private *i915,
 				       u32 guc_wopcm_base, u32 guc_wopcm_size,
 				       u32 huc_fw_size)
 {
-	int err = 0;
+	u32 size;
+
+	if (IS_GEN9(i915) || IS_CNL_REVID(i915, CNL_REVID_A0, CNL_REVID_A0)) {
+		size = gen9_size_for_dword_gap_restriction(guc_wopcm_base,
+							   guc_wopcm_size);
+		if (size)
+			goto err;
+
+		size = gen9_size_for_huc_restriction(guc_wopcm_size,
+						     huc_fw_size);
+		if (size)
+			goto err;
+	}
 
-	if (IS_GEN9(i915))
-		err = gen9_check_dword_gap(guc_wopcm_base, guc_wopcm_size);
+	return 0;
 
-	if (!err &&
-	    (IS_GEN9(i915) || IS_CNL_REVID(i915, CNL_REVID_A0, CNL_REVID_A0)))
-		err = gen9_check_huc_fw_fits(guc_wopcm_size, huc_fw_size);
+err:
+	DRM_ERROR("GuC WOPCM size %uKiB is too small. %uKiB more needed.\n",
+		  guc_wopcm_size / 1024,
+		  size / 1024);
 
-	return err;
+	return -E2BIG;
 }
 
 /**
-- 
2.14.3