[Intel-gfx] [PATCH] drm/i915/tgl: Program BW_BUDDY registers during display init

[Matt Roper]

Gen12 can improve bandwidth efficiency by pairing up memory requests
with similar addresses.  We need to program the BW_BUDDY1 and BW_BUDDY2
registers according to the memory configuration during display
initialization to take advantage of this capability.

The magic numbers we program here feel like something that could
definitely change on future platforms, so let's use a table-based
programming scheme to make this easy to extend in the future.

Bspec: 49189
Bspec: 49218
Cc: Stanislav Lisovskiy <stanislav.lisovskiy at intel.com>
Cc: Ville Syrjala <ville.syrjala at linux.intel.com>
Cc: Lucas De Marchi <lucas.demarchi at intel.com>
Signed-off-by: Matt Roper <matthew.d.roper at intel.com>
---
 .../drm/i915/display/intel_display_power.c    | 40 +++++++++++++++++++
 drivers/gpu/drm/i915/i915_reg.h               |  8 ++++
 2 files changed, 48 insertions(+)

diff --git a/drivers/gpu/drm/i915/display/intel_display_power.c b/drivers/gpu/drm/i915/display/intel_display_power.c
index ce1b64f4dd44..1d26f741b5b4 100644
--- a/drivers/gpu/drm/i915/display/intel_display_power.c
+++ b/drivers/gpu/drm/i915/display/intel_display_power.c
@@ -4781,6 +4781,42 @@ static void cnl_display_core_uninit(struct drm_i915_private *dev_priv)
 	intel_combo_phy_uninit(dev_priv);
 }
 
+struct buddy_page_mask {
+	u8 num_channels;
+	enum intel_dram_type type;
+	u32 page_mask;
+};
+
+const struct buddy_page_mask tgl_buddy_page_masks[] = {
+	{ 1, INTEL_DRAM_LPDDR4, 0xE },
+	{ 1, INTEL_DRAM_DDR4,   0xF },
+	{ 2, INTEL_DRAM_LPDDR4, 0x1C },
+	{ 2, INTEL_DRAM_DDR4,   0x1F },
+	{}
+};
+
+static void tgl_arbiter_init(struct drm_i915_private *dev_priv)
+{
+	enum intel_dram_type type = dev_priv->dram_info.type;
+	u8 num_channels = dev_priv->dram_info.num_channels;
+	const struct buddy_page_mask *table = tgl_buddy_page_masks;
+	int i;
+
+	for (i = 0; table[i].page_mask != 0; i++)
+		if (table[i].num_channels == num_channels &&
+		    table[i].type == type)
+			break;
+
+	if (table[i].page_mask == 0) {
+		DRM_DEBUG_DRIVER("Unknown memory configuration; disabling address buddy logic.\n");
+		I915_WRITE(BW_BUDDY1_CTL, BW_BUDDY_DISABLE);
+		I915_WRITE(BW_BUDDY2_CTL, BW_BUDDY_DISABLE);
+	} else {
+		I915_WRITE(BW_BUDDY1_PAGE_MASK, table[i].page_mask);
+		I915_WRITE(BW_BUDDY2_PAGE_MASK, table[i].page_mask);
+	}
+}
+
 static void icl_display_core_init(struct drm_i915_private *dev_priv,
 				  bool resume)
 {
@@ -4813,6 +4849,10 @@ static void icl_display_core_init(struct drm_i915_private *dev_priv,
 	/* 6. Setup MBUS. */
 	icl_mbus_init(dev_priv);
 
+	/* 7. Program arbiter BW_BUDDY registers */
+	if (INTEL_GEN(dev_priv) >= 12)
+		tgl_arbiter_init(dev_priv);
+
 	if (resume && dev_priv->csr.dmc_payload)
 		intel_csr_load_program(dev_priv);
 }
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 1a6376a97d48..082190c2dc48 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -7765,6 +7765,14 @@ enum {
 #define GEN7_MSG_CTL	_MMIO(0x45010)
 #define  WAIT_FOR_PCH_RESET_ACK		(1 << 1)
 #define  WAIT_FOR_PCH_FLR_ACK		(1 << 0)
+
+#define BW_BUDDY1_CTL			_MMIO(0x45140)
+#define BW_BUDDY2_CTL			_MMIO(0x45150)
+#define   BW_BUDDY_DISABLE		REG_BIT(31)
+
+#define BW_BUDDY1_PAGE_MASK		_MMIO(0x45144)
+#define BW_BUDDY2_PAGE_MASK		_MMIO(0x45154)
+
 #define HSW_NDE_RSTWRN_OPT	_MMIO(0x46408)
 #define  RESET_PCH_HANDSHAKE_ENABLE	(1 << 4)
 
-- 
2.23.0