[PATCH 2/2] drm/i915: use the HDMI DDI buffer translations from VBT

[Paulo Zanoni <przanoni@gmail.com>]

From: Paulo Zanoni <paulo.r.zanoni@intel.com>

We currently use the recommended values from BSpec, but the VBT
specifies the correct value to use for the hardware we have, so use
it. We also fall back to the recommended value in case we can't find
the VBT.

In addition, this code also provides some infrastructure to parse more
information about the DDI ports. There's a lot more information we
could extract and use in the future.

Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
---
 drivers/gpu/drm/i915/i915_drv.h   |  6 ++++
 drivers/gpu/drm/i915/intel_bios.c | 65 +++++++++++++++++++++++++++++++++++++++
 drivers/gpu/drm/i915/intel_ddi.c  | 24 +++++++++++++--
 3 files changed, 93 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 08fe1b6..645dd74 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1039,6 +1039,10 @@ enum modeset_restore {
 	MODESET_SUSPENDED,
 };
 
+struct ddi_vbt_port_info {
+	uint8_t hdmi_level_shift;
+};
+
 struct intel_vbt_data {
 	struct drm_display_mode *lfp_lvds_vbt_mode; /* if any */
 	struct drm_display_mode *sdvo_lvds_vbt_mode; /* if any */
@@ -1068,6 +1072,8 @@ struct intel_vbt_data {
 
 	int child_dev_num;
 	union child_device_config *child_dev;
+
+	struct ddi_vbt_port_info ddi_port_info[5];
 };
 
 enum intel_ddb_partitioning {
diff --git a/drivers/gpu/drm/i915/intel_bios.c b/drivers/gpu/drm/i915/intel_bios.c
index 8a27925..a5cb665 100644
--- a/drivers/gpu/drm/i915/intel_bios.c
+++ b/drivers/gpu/drm/i915/intel_bios.c
@@ -568,6 +568,69 @@ parse_edp(struct drm_i915_private *dev_priv, struct bdb_header *bdb)
 	}
 }
 
+static void parse_ddi_port(struct drm_i915_private *dev_priv, enum port port,
+			   struct bdb_header *bdb)
+{
+	union child_device_config *it, *child = NULL;
+	struct ddi_vbt_port_info *info = &dev_priv->vbt.ddi_port_info[port];
+	uint8_t hdmi_level_shift;
+	int i, j;
+	int dvo_ports[][2] = {
+		{0, 10}, {1, 7}, {2, 8}, {3, 9}, {6, /* Unused */ 0},
+	};
+	int n_dvo_ports[] = {2, 2, 2, 2, 1};
+
+	/* Find the child device to use, abort if more than one found. */
+	for (i = 0; i < dev_priv->vbt.child_dev_num; i++) {
+		it = dev_priv->vbt.child_dev + i;
+
+		for (j = 0; j < n_dvo_ports[port]; j++) {
+			if (it->common.dvo_port == dvo_ports[port][j]) {
+				if (child) {
+					DRM_ERROR("More than one child device for port %c in VBT.\n",
+						   port_name(port));
+					return;
+				}
+				child = it;
+			}
+		}
+	}
+	if (!child)
+		return;
+
+	if (bdb->version >= 158) {
+		/* The VBT HDMI level shift values match the table we have. */
+		hdmi_level_shift = child->raw[7] & 0xF;
+		if (hdmi_level_shift < 0xC) {
+			DRM_DEBUG_KMS("VBT HDMI level shift for port %c: %d\n",
+				      port_name(port),
+				      hdmi_level_shift);
+			info->hdmi_level_shift = hdmi_level_shift;
+		}
+	}
+}
+
+static void parse_ddi_ports(struct drm_i915_private *dev_priv,
+			    struct bdb_header *bdb)
+{
+	enum port port;
+
+	/* Default values, in case something is wrong with the VBT. */
+	for (port = PORT_A; port <= PORT_E; port++) {
+		/* Recommended BSpec default: 800mV 0dB. */
+		dev_priv->vbt.ddi_port_info[port].hdmi_level_shift = 6;
+	}
+
+	if (!dev_priv->vbt.child_dev_num)
+		return;
+
+	if (bdb->version < 155)
+		return;
+
+	for (port = PORT_A; port <= PORT_E; port++)
+		parse_ddi_port(dev_priv, port, bdb);
+}
+
 static void
 parse_device_mapping(struct drm_i915_private *dev_priv,
 		       struct bdb_header *bdb)
@@ -745,6 +808,8 @@ intel_parse_bios(struct drm_device *dev)
 	parse_device_mapping(dev_priv, bdb);
 	parse_driver_features(dev_priv, bdb);
 	parse_edp(dev_priv, bdb);
+	if (HAS_DDI(dev))
+		parse_ddi_ports(dev_priv, bdb);
 
 	if (bios)
 		pci_unmap_rom(pdev, bios);
diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
index 63aca49..ece226d 100644
--- a/drivers/gpu/drm/i915/intel_ddi.c
+++ b/drivers/gpu/drm/i915/intel_ddi.c
@@ -42,7 +42,6 @@ static const u32 hsw_ddi_translations_dp[] = {
 	0x80C30FFF, 0x000B0000,
 	0x00FFFFFF, 0x00040006,
 	0x80D75FFF, 0x000B0000,
-	0x00FFFFFF, 0x00040006		/* HDMI parameters */
 };
 
 static const u32 hsw_ddi_translations_fdi[] = {
@@ -55,7 +54,22 @@ static const u32 hsw_ddi_translations_fdi[] = {
 	0x00C30FFF, 0x001E0000,
 	0x00FFFFFF, 0x00060006,
 	0x00D75FFF, 0x001E0000,
-	0x00FFFFFF, 0x00040006		/* HDMI parameters */
+};
+
+static const u32 hsw_ddi_translations_hdmi[] = {
+				/* Idx	NT mV diff	T mV diff	db  */
+	0x00FFFFFF, 0x0006000E, /* 0:	400		400		0   */
+	0x00E79FFF, 0x000E000C, /* 1:	400		500		2   */
+	0x00D75FFF, 0x0005000A, /* 2:	400		600		3.5 */
+	0x00FFFFFF, 0x0005000A, /* 3:	600		600		0   */
+	0x00E79FFF, 0x001D0007, /* 4:	600		750		2   */
+	0x00D75FFF, 0x000C0004, /* 5:	600		900		3.5 */
+	0x00FFFFFF, 0x00040006, /* 6:	800		800		0   */
+	0x80E79FFF, 0x00030002, /* 7:	800		1000		2   */
+	0x00FFFFFF, 0x00140005, /* 8:	850		850		0   */
+	0x00FFFFFF, 0x000C0004, /* 9:	900		900		0   */
+	0x00FFFFFF, 0x001C0003, /* 10:	950		950		0   */
+	0x80FFFFFF, 0x00030002, /* 11:	1000		1000		0   */
 };
 
 static enum port intel_ddi_get_encoder_port(struct intel_encoder *intel_encoder)
@@ -92,12 +106,18 @@ static void intel_prepare_ddi_buffers(struct drm_device *dev, enum port port)
 	const u32 *ddi_translations = (port == PORT_E) ?
 		hsw_ddi_translations_fdi :
 		hsw_ddi_translations_dp;
+	int hdmi_level = dev_priv->vbt.ddi_port_info[port].hdmi_level_shift;
 
 	for (i = 0, reg = DDI_BUF_TRANS(port);
 	     i < ARRAY_SIZE(hsw_ddi_translations_fdi); i++) {
 		I915_WRITE(reg, ddi_translations[i]);
 		reg += 4;
 	}
+	/* Entry 9 is for HDMI: */
+	for (i = 0; i < 2; i++) {
+		I915_WRITE(reg, hsw_ddi_translations_hdmi[hdmi_level * 2 + i]);
+		reg += 4;
+	}
 }
 
 /* Program DDI buffers translations for DP. By default, program ports A-D in DP
-- 
1.8.1.2