drm/i915/bios: parse compression parameters block

Check for child devices that specify compression, and store the device
specific compression parameters in the display device data struct for
later use. Warn if compression is requested but not available.

Use fairly rigid checks for compression data for starters. These can be
made more dynamic later.

Log about DSC presence in DDI port parse, though this is not universal
across platforms or port types (DSI).

v2: amended debug logging

Bspec: 29885
Cc: Vandita Kulkarni <vandita.kulkarni@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NVandita Kulkarni <vandita.kulkarni@intel.com>
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/357d685ba047faf2285138c2f7014a8dee9a12b7.1575974743.git.jani.nikula@intel.com

drivers/gpu/drm/i915/display/intel_bios.c

@@ -61,6 +61,7 @@
 /* Wrapper for VBT child device config */
 struct display_device_data {
 	struct child_device_config child;
+	struct dsc_compression_parameters_entry *dsc;
 	struct list_head node;
 };
 
@@ -1366,6 +1367,57 @@ parse_mipi_sequence(struct drm_i915_private *dev_priv,
 	memset(dev_priv->vbt.dsi.sequence, 0, sizeof(dev_priv->vbt.dsi.sequence));
 }
 
+static void
+parse_compression_parameters(struct drm_i915_private *i915,
+			     const struct bdb_header *bdb)
+{
+	const struct bdb_compression_parameters *params;
+	struct display_device_data *devdata;
+	const struct child_device_config *child;
+	u16 block_size;
+	int index;
+
+	if (bdb->version < 198)
+		return;
+
+	params = find_section(bdb, BDB_COMPRESSION_PARAMETERS);
+	if (params) {
+		/* Sanity checks */
+		if (params->entry_size != sizeof(params->data[0])) {
+			DRM_DEBUG_KMS("VBT: unsupported compression param entry size\n");
+			return;
+		}
+
+		block_size = get_blocksize(params);
+		if (block_size < sizeof(*params)) {
+			DRM_DEBUG_KMS("VBT: expected 16 compression param entries\n");
+			return;
+		}
+	}
+
+	list_for_each_entry(devdata, &i915->vbt.display_devices, node) {
+		child = &devdata->child;
+
+		if (!child->compression_enable)
+			continue;
+
+		if (!params) {
+			DRM_DEBUG_KMS("VBT: compression params not available\n");
+			continue;
+		}
+
+		if (child->compression_method_cps) {
+			DRM_DEBUG_KMS("VBT: CPS compression not supported\n");
+			continue;
+		}
+
+		index = child->compression_structure_index;
+
+		devdata->dsc = kmemdup(&params->data[index],
+				       sizeof(*devdata->dsc), GFP_KERNEL);
+	}
+}
+
 static u8 translate_iboost(u8 val)
 {
 	static const u8 mapping[] = { 1, 3, 7 }; /* See VBT spec */
@@ -1598,10 +1650,11 @@ static void parse_ddi_port(struct drm_i915_private *dev_priv,
 	if (bdb_version >= 209)
 		info->supports_tbt = child->tbt;
 
-	DRM_DEBUG_KMS("Port %c VBT info: CRT:%d DVI:%d HDMI:%d DP:%d eDP:%d LSPCON:%d USB-Type-C:%d TBT:%d\n",
+	DRM_DEBUG_KMS("Port %c VBT info: CRT:%d DVI:%d HDMI:%d DP:%d eDP:%d LSPCON:%d USB-Type-C:%d TBT:%d DSC:%d\n",
 		      port_name(port), is_crt, is_dvi, is_hdmi, is_dp, is_edp,
 		      HAS_LSPCON(dev_priv) && child->lspcon,
-		      info->supports_typec_usb, info->supports_tbt);
+		      info->supports_typec_usb, info->supports_tbt,
+		      devdata->dsc != NULL);
 
 	if (is_edp && is_dvi)
 		DRM_DEBUG_KMS("Internal DP port %c is TMDS compatible\n",
@@ -2037,6 +2090,9 @@ void intel_bios_init(struct drm_i915_private *dev_priv)
 	parse_mipi_config(dev_priv, bdb);
 	parse_mipi_sequence(dev_priv, bdb);
 
+	/* Depends on child device list */
+	parse_compression_parameters(dev_priv, bdb);
+
 	/* Further processing on pre-parsed data */
 	parse_sdvo_device_mapping(dev_priv, bdb->version);
 	parse_ddi_ports(dev_priv, bdb->version);
@@ -2060,6 +2116,7 @@ void intel_bios_driver_remove(struct drm_i915_private *dev_priv)
 
 	list_for_each_entry_safe(devdata, n, &dev_priv->vbt.display_devices, node) {
 		list_del(&devdata->node);
+		kfree(devdata->dsc);
 		kfree(devdata);
 	}
 

drivers/gpu/drm/i915/display/intel_vbt_defs.h

@@ -369,7 +369,7 @@ struct child_device_config {
 			u16 dtd_buf_ptr;			/* 161 */
 			u8 edidless_efp:1;			/* 161 */
 			u8 compression_enable:1;		/* 198 */
-			u8 compression_method:1;		/* 198 */
+			u8 compression_method_cps:1;		/* 198 */
 			u8 ganged_edp:1;			/* 202 */
 			u8 reserved0:4;
 			u8 compression_structure_index:4;	/* 198 */