[PATCH 5/8] drm/i915/guc: Use GuC FW size and HW restrictions to determine WOPCM partition

[Michał Winiarski]

We need GuC to load HuC, but it's also possible for GuC to operate on
its own. We don't know what the size of HuC FW may be, so, not wanting
to make any platform-specific hardcoded guesses, we assume that its size
is 0... Which is a very bad approximation.
This has a very unfortunate consequence - once we've booted with GuC and
no HuC, we'll never be able to load HuC (unless we reboot, since the
registers are locked).
Rather than using unknown values in our computations - let's partition
based on GuC size.
We have one HW restriction where we're using HuC size (GuC size needs to
be roughly similar to HuC size - which may be unknown at this point),
luckily, another HW restriction makes it very unlikely to run in any
sort of issues in this case.

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 | 61 ++++++++++++++++++++++----------------
 1 file changed, 35 insertions(+), 26 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_wopcm.c b/drivers/gpu/drm/i915/intel_wopcm.c
index 7d4a550d051d..6c2ca3ba7ea6 100644
--- a/drivers/gpu/drm/i915/intel_wopcm.c
+++ b/drivers/gpu/drm/i915/intel_wopcm.c
@@ -178,7 +178,22 @@ static int check_ctx_rsvd_fits(struct intel_wopcm *wopcm, u32 ctx_rsvd)
 	return 0;
 }
 
-static int wopcm_check_hw_restrictions(struct intel_wopcm *wopcm)
+static inline void
+__guc_region_grow(struct intel_wopcm *wopcm, u32 size)
+{
+	/*
+	 * We're growing guc region in the direction of lower addresses.
+	 * We need to use multiples of base alignment, because it has more
+	 * strict alignment rules.
+	 */
+	size = DIV_ROUND_UP(size, 2);
+	size = ALIGN(size, GUC_WOPCM_OFFSET_ALIGNMENT);
+
+	wopcm->guc.base -= size;
+	wopcm->guc.size += size;
+}
+
+static void wopcm_adjust_for_hw_restrictions(struct intel_wopcm *wopcm)
 {
 	struct drm_i915_private *i915 = wopcm_to_i915(wopcm);
 	u32 huc_fw_size = intel_uc_fw_get_upload_size(&i915->huc.fw);
@@ -189,22 +204,19 @@ static int wopcm_check_hw_restrictions(struct intel_wopcm *wopcm)
 							   wopcm->guc.base,
 							   wopcm->guc.size);
 		if (size)
-			goto err;
+			__guc_region_grow(wopcm, size);
 
 		size = gen9_size_for_huc_restriction(wopcm->guc.size,
 						     huc_fw_size);
 		if (size)
-			goto err;
-	}
-
-	return 0;
+			__guc_region_grow(wopcm, size);
 
-err:
-	DRM_ERROR("GuC WOPCM size %uKiB is too small. %uKiB more needed.\n",
-		  wopcm->guc.size / 1024,
-		  size / 1024);
-
-	return -E2BIG;
+		GEM_BUG_ON(gen9_size_for_dword_gap_restriction(i915,
+							       wopcm->guc.base,
+							       wopcm->guc.size));
+		GEM_BUG_ON(gen9_size_for_huc_restriction(wopcm->guc.size,
+							 huc_fw_size));
+	}
 }
 
 static bool wopcm_check_components_fit(struct intel_wopcm *wopcm)
@@ -230,21 +242,16 @@ static bool wopcm_check_components_fit(struct intel_wopcm *wopcm)
 	return 0;
 }
 
-static int wopcm_guc_init(struct intel_wopcm *wopcm)
+static int wopcm_guc_region_init(struct intel_wopcm *wopcm)
 {
 	struct drm_i915_private *dev_priv = wopcm_to_i915(wopcm);
-	u32 huc_fw_size = intel_uc_fw_get_upload_size(&dev_priv->huc.fw);
+	u32 guc_fw_size = intel_uc_fw_get_upload_size(&dev_priv->guc.fw);
 	u32 ctx_rsvd = context_reserved_size(dev_priv);
 
-	wopcm->guc.base = ALIGN(huc_fw_size_in_wopcm(huc_fw_size),
-				GUC_WOPCM_OFFSET_ALIGNMENT);
+	wopcm->guc.size = guc_fw_size_in_wopcm(guc_fw_size);
 
-	wopcm->guc.size = ALIGN(wopcm->size - wopcm->guc.base - ctx_rsvd,
-				PAGE_SIZE);
-
-	DRM_DEBUG_DRIVER("GuC WOPCM Region: [%uKiB, %uKiB)\n",
-			 wopcm->guc.base / 1024,
-			 (wopcm->guc.base + wopcm->guc.size) / 1024);
+	wopcm->guc.base = ALIGN_DOWN(wopcm->size - ctx_rsvd - wopcm->guc.size,
+				     GUC_WOPCM_OFFSET_ALIGNMENT);
 
 	return 0;
 }
@@ -267,18 +274,20 @@ int intel_wopcm_init(struct intel_wopcm *wopcm)
 
 	GEM_BUG_ON(!wopcm->size);
 
-	err = wopcm_guc_init(wopcm);
+	err = wopcm_guc_region_init(wopcm);
 	if (err)
 		return err;
 
-	err = wopcm_check_hw_restrictions(wopcm);
-	if (err)
-		return err;
+	wopcm_adjust_for_hw_restrictions(wopcm);
 
 	err = wopcm_check_components_fit(wopcm);
 	if (err)
 		return err;
 
+	DRM_DEBUG_DRIVER("GuC WOPCM Region: [%uKiB, %uKiB)\n",
+			 wopcm->guc.base / 1024,
+			 (wopcm->guc.base + wopcm->guc.size) / 1024);
+
 	return 0;
 }
 
-- 
2.14.3