drm/i915: Add ddb size field to device info structure

Adding the ddb size into the devide info will avoid
platform checks while computing wm.

v2: Added comment and WARN_ON if ddb size is zero.(Jani)
v3: Added WARN_ON at the right place.(Jani)

Suggested-by: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com>
Signed-off-by: Deepak M <m.deepak@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1473931870-7724-1-git-send-email-m.deepak@intel.com

drivers/gpu/drm/i915/i915_drv.h

@@ -710,6 +710,7 @@ struct intel_device_info {
 	u8 ring_mask; /* Rings supported by the HW */
 	u8 num_rings;
 	DEV_INFO_FOR_EACH_FLAG(DEFINE_FLAG, SEP_SEMICOLON);
+	u16 ddb_size; /* in blocks */
 	/* Register offsets for the various display pipes and transcoders */
 	int pipe_offsets[I915_MAX_TRANSCODERS];
 	int trans_offsets[I915_MAX_TRANSCODERS];

drivers/gpu/drm/i915/i915_pci.c

@@ -328,6 +328,7 @@ static const struct intel_device_info intel_skylake_info = {
 	.gen = 9,
 	.has_csr = 1,
 	.has_guc = 1,
+	.ddb_size = 896,
 };
 
 static const struct intel_device_info intel_skylake_gt3_info = {
@@ -336,6 +337,7 @@ static const struct intel_device_info intel_skylake_gt3_info = {
 	.gen = 9,
 	.has_csr = 1,
 	.has_guc = 1,
+	.ddb_size = 896,
 	.ring_mask = RENDER_RING | BSD_RING | BLT_RING | VEBOX_RING | BSD2_RING,
 };
 
@@ -358,6 +360,7 @@ static const struct intel_device_info intel_broxton_info = {
 	.has_hw_contexts = 1,
 	.has_logical_ring_contexts = 1,
 	.has_guc = 1,
+	.ddb_size = 512,
 	GEN_DEFAULT_PIPEOFFSETS,
 	IVB_CURSOR_OFFSETS,
 	BDW_COLORS,
@@ -369,6 +372,7 @@ static const struct intel_device_info intel_kabylake_info = {
 	.gen = 9,
 	.has_csr = 1,
 	.has_guc = 1,
+	.ddb_size = 896,
 };
 
 static const struct intel_device_info intel_kabylake_gt3_info = {
@@ -377,6 +381,7 @@ static const struct intel_device_info intel_kabylake_gt3_info = {
 	.gen = 9,
 	.has_csr = 1,
 	.has_guc = 1,
+	.ddb_size = 896,
 	.ring_mask = RENDER_RING | BSD_RING | BLT_RING | VEBOX_RING | BSD2_RING,
 };
 

drivers/gpu/drm/i915/intel_pm.c

@@ -2853,13 +2853,6 @@ bool ilk_disable_lp_wm(struct drm_device *dev)
 	return _ilk_disable_lp_wm(dev_priv, WM_DIRTY_LP_ALL);
 }
 
-/*
- * On gen9, we need to allocate Display Data Buffer (DDB) portions to the
- * different active planes.
- */
-
-#define SKL_DDB_SIZE		896	/* in blocks */
-#define BXT_DDB_SIZE		512
 #define SKL_SAGV_BLOCK_TIME	30 /* µs */
 
 /*
@@ -3057,10 +3050,8 @@ skl_ddb_get_pipe_allocation_limits(struct drm_device *dev,
 	else
 		*num_active = hweight32(dev_priv->active_crtcs);
 
-	if (IS_BROXTON(dev))
-		ddb_size = BXT_DDB_SIZE;
-	else
-		ddb_size = SKL_DDB_SIZE;
+	ddb_size = INTEL_INFO(dev_priv)->ddb_size;
+	WARN_ON(ddb_size == 0);
 
 	ddb_size -= 4; /* 4 blocks for bypass path allocation */