drm/i915/vbt: Handle generic DTD block

VBT revision 229 adds a new "Generic DTD" block 58 and deprecates the
old LFP panel mode data in block 42.  Let's start parsing this block to
fill in the panel fixed mode on devices with a >=229 VBT.

v2:
 * Update according to the recent updates:
    - DTD size is now 16 bits instead of 24
    - polarity is now just a single bit for hsync and vsync and is
      properly documented
 * Minor checkpatch fix

v3:
 * Now that panel options are parsed separately from the previous patch,
   move generic DTD parsing into a function parallel to
   parse_lfp_panel_dtd.  We'll still fall back to looking at the legacy
   LVDS timing block if the generic DTD fails.  (Jani)
 * Don't forget to actually set lfp_lvds_vbt_mode!  (Jani)
 * Drop "bdb_" prefix from dtd entry structure.  (Jani)
 * Follow C99 standard for structure's flexible array member.  (Jani)

v4:
 * Add "positive" to polarity field names for clarity.  (Jani)
 * Move VBT version check and fallback to legacy DTD parsing logic to a
   helper to keep top-level VBT parsing uncluttered.  (Jani)
 * Restructure reserved bit packing at end of generic_dtd_entry from
   "u32 rsvd:24" to "u8 rsvd[3]" to prevent copy/paste mistakes in the
   future.  (Jani)

Bspec: 54751
Bspec: 20148
Cc: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191115165132.9472-3-matthew.d.roper@intel.com

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

@@ -296,7 +296,7 @@ parse_lfp_panel_dtd(struct drm_i915_private *dev_priv,
 
 	dev_priv->vbt.lfp_lvds_vbt_mode = panel_fixed_mode;
 
-	DRM_DEBUG_KMS("Found panel mode in BIOS VBT tables:\n");
+	DRM_DEBUG_KMS("Found panel mode in BIOS VBT legacy lfp table:\n");
 	drm_mode_debug_printmodeline(panel_fixed_mode);
 
 	fp_timing = get_lvds_fp_timing(bdb, lvds_lfp_data,
@@ -313,6 +313,98 @@ parse_lfp_panel_dtd(struct drm_i915_private *dev_priv,
 	}
 }
 
+static void
+parse_generic_dtd(struct drm_i915_private *dev_priv,
+		  const struct bdb_header *bdb)
+{
+	const struct bdb_generic_dtd *generic_dtd;
+	const struct generic_dtd_entry *dtd;
+	struct drm_display_mode *panel_fixed_mode;
+	int num_dtd;
+
+	generic_dtd = find_section(bdb, BDB_GENERIC_DTD);
+	if (!generic_dtd)
+		return;
+
+	if (generic_dtd->gdtd_size < sizeof(struct generic_dtd_entry)) {
+		DRM_ERROR("GDTD size %u is too small.\n",
+			  generic_dtd->gdtd_size);
+		return;
+	} else if (generic_dtd->gdtd_size !=
+		   sizeof(struct generic_dtd_entry)) {
+		DRM_ERROR("Unexpected GDTD size %u\n", generic_dtd->gdtd_size);
+		/* DTD has unknown fields, but keep going */
+	}
+
+	num_dtd = (get_blocksize(generic_dtd) -
+		   sizeof(struct bdb_generic_dtd)) / generic_dtd->gdtd_size;
+	if (dev_priv->vbt.panel_type > num_dtd) {
+		DRM_ERROR("Panel type %d not found in table of %d DTD's\n",
+			  dev_priv->vbt.panel_type, num_dtd);
+		return;
+	}
+
+	dtd = &generic_dtd->dtd[dev_priv->vbt.panel_type];
+
+	panel_fixed_mode = kzalloc(sizeof(*panel_fixed_mode), GFP_KERNEL);
+	if (!panel_fixed_mode)
+		return;
+
+	panel_fixed_mode->hdisplay = dtd->hactive;
+	panel_fixed_mode->hsync_start =
+		panel_fixed_mode->hdisplay + dtd->hfront_porch;
+	panel_fixed_mode->hsync_end =
+		panel_fixed_mode->hsync_start + dtd->hsync;
+	panel_fixed_mode->htotal = panel_fixed_mode->hsync_end;
+
+	panel_fixed_mode->vdisplay = dtd->vactive;
+	panel_fixed_mode->vsync_start =
+		panel_fixed_mode->vdisplay + dtd->vfront_porch;
+	panel_fixed_mode->vsync_end =
+		panel_fixed_mode->vsync_start + dtd->vsync;
+	panel_fixed_mode->vtotal = panel_fixed_mode->vsync_end;
+
+	panel_fixed_mode->clock = dtd->pixel_clock;
+	panel_fixed_mode->width_mm = dtd->width_mm;
+	panel_fixed_mode->height_mm = dtd->height_mm;
+
+	panel_fixed_mode->type = DRM_MODE_TYPE_PREFERRED;
+	drm_mode_set_name(panel_fixed_mode);
+
+	if (dtd->hsync_positive_polarity)
+		panel_fixed_mode->flags |= DRM_MODE_FLAG_PHSYNC;
+	else
+		panel_fixed_mode->flags |= DRM_MODE_FLAG_NHSYNC;
+
+	if (dtd->vsync_positive_polarity)
+		panel_fixed_mode->flags |= DRM_MODE_FLAG_PVSYNC;
+	else
+		panel_fixed_mode->flags |= DRM_MODE_FLAG_NVSYNC;
+
+	DRM_DEBUG_KMS("Found panel mode in BIOS VBT generic dtd table:\n");
+	drm_mode_debug_printmodeline(panel_fixed_mode);
+
+	dev_priv->vbt.lfp_lvds_vbt_mode = panel_fixed_mode;
+}
+
+static void
+parse_panel_dtd(struct drm_i915_private *dev_priv,
+		const struct bdb_header *bdb)
+{
+	/*
+	 * Older VBTs provided provided DTD information for internal displays
+	 * through the "LFP panel DTD" block (42).  As of VBT revision 229,
+	 * that block is now deprecated and DTD information should be provided
+	 * via a newer "generic DTD" block (58).  Just to be safe, we'll
+	 * try the new generic DTD block first on VBT >= 229, but still fall
+	 * back to trying the old LFP block if that fails.
+	 */
+	if (bdb->version >= 229)
+		parse_generic_dtd(dev_priv, bdb);
+	if (!dev_priv->vbt.lfp_lvds_vbt_mode)
+		parse_lfp_panel_dtd(dev_priv, bdb);
+}
+
 static void
 parse_lfp_backlight(struct drm_i915_private *dev_priv,
 		    const struct bdb_header *bdb)
@@ -1877,7 +1969,7 @@ void intel_bios_init(struct drm_i915_private *dev_priv)
 	parse_general_features(dev_priv, bdb);
 	parse_general_definitions(dev_priv, bdb);
 	parse_panel_options(dev_priv, bdb);
-	parse_lfp_panel_dtd(dev_priv, bdb);
+	parse_panel_dtd(dev_priv, bdb);
 	parse_lfp_backlight(dev_priv, bdb);
 	parse_sdvo_panel_data(dev_priv, bdb);
 	parse_driver_features(dev_priv, bdb);

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

@@ -115,6 +115,7 @@ enum bdb_block_id {
 	BDB_MIPI_CONFIG			= 52,
 	BDB_MIPI_SEQUENCE		= 53,
 	BDB_COMPRESSION_PARAMETERS	= 56,
+	BDB_GENERIC_DTD			= 58,
 	BDB_SKIP			= 254, /* VBIOS private block, ignore */
 };
 
@@ -863,4 +864,34 @@ struct bdb_compression_parameters {
 	struct dsc_compression_parameters_entry data[16];
 } __packed;
 
+/*
+ * Block 58 - Generic DTD Block
+ */
+
+struct generic_dtd_entry {
+	u32 pixel_clock;
+	u16 hactive;
+	u16 hblank;
+	u16 hfront_porch;
+	u16 hsync;
+	u16 vactive;
+	u16 vblank;
+	u16 vfront_porch;
+	u16 vsync;
+	u16 width_mm;
+	u16 height_mm;
+
+	/* Flags */
+	u8 rsvd_flags:6;
+	u8 vsync_positive_polarity:1;
+	u8 hsync_positive_polarity:1;
+
+	u8 rsvd[3];
+} __packed;
+
+struct bdb_generic_dtd {
+	u16 gdtd_size;
+	struct generic_dtd_entry dtd[];	/* up to 24 DTD's */
+} __packed;
+
 #endif /* _INTEL_VBT_DEFS_H_ */