drm/i915: constify find_section in VBT parsing

Make input and output of find_section const, and fix the fallout. We
shouldn't modify the VBT, so make the compiler help us here.
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Reviewed-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_bios.c

@@ -36,10 +36,11 @@
 
 static int panel_type;
 
-static void *
-find_section(struct bdb_header *bdb, int section_id)
+static const void *
+find_section(const void *_bdb, int section_id)
 {
-	u8 *base = (u8 *)bdb;
+	const struct bdb_header *bdb = _bdb;
+	const u8 *base = _bdb;
 	int index = 0;
 	u16 total, current_size;
 	u8 current_id;
@@ -53,7 +54,7 @@ find_section(struct bdb_header *bdb, int section_id)
 		current_id = *(base + index);
 		index++;
 
-		current_size = *((u16 *)(base + index));
+		current_size = *((const u16 *)(base + index));
 		index += 2;
 
 		if (index + current_size > total)
@@ -69,7 +70,7 @@ find_section(struct bdb_header *bdb, int section_id)
 }
 
 static u16
-get_blocksize(void *p)
+get_blocksize(const void *p)
 {
 	u16 *block_ptr, block_size;
 
@@ -350,7 +351,7 @@ static void
 parse_sdvo_panel_data(struct drm_i915_private *dev_priv,
 		      struct bdb_header *bdb)
 {
-	struct lvds_dvo_timing *dvo_timing;
+	const struct lvds_dvo_timing *dvo_timing;
 	struct drm_display_mode *panel_fixed_mode;
 	int index;
 
@@ -361,7 +362,7 @@ parse_sdvo_panel_data(struct drm_i915_private *dev_priv,
 	}
 
 	if (index == -1) {
-		struct bdb_sdvo_lvds_options *sdvo_lvds_options;
+		const struct bdb_sdvo_lvds_options *sdvo_lvds_options;
 
 		sdvo_lvds_options = find_section(bdb, BDB_SDVO_LVDS_OPTIONS);
 		if (!sdvo_lvds_options)
@@ -405,7 +406,7 @@ parse_general_features(struct drm_i915_private *dev_priv,
 		       struct bdb_header *bdb)
 {
 	struct drm_device *dev = dev_priv->dev;
-	struct bdb_general_features *general;
+	const struct bdb_general_features *general;
 
 	general = find_section(bdb, BDB_GENERAL_FEATURES);
 	if (general) {
@@ -430,7 +431,7 @@ static void
 parse_general_definitions(struct drm_i915_private *dev_priv,
 			  struct bdb_header *bdb)
 {
-	struct bdb_general_definitions *general;
+	const struct bdb_general_definitions *general;
 
 	general = find_section(bdb, BDB_GENERAL_DEFINITIONS);
 	if (general) {
@@ -447,10 +448,10 @@ parse_general_definitions(struct drm_i915_private *dev_priv,
 	}
 }
 
-static union child_device_config *
-child_device_ptr(struct bdb_general_definitions *p_defs, int i)
+static const union child_device_config *
+child_device_ptr(const struct bdb_general_definitions *p_defs, int i)
 {
-	return (void *) &p_defs->devices[i * p_defs->child_dev_size];
+	return (const void *) &p_defs->devices[i * p_defs->child_dev_size];
 }
 
 static void
@@ -458,8 +459,8 @@ parse_sdvo_device_mapping(struct drm_i915_private *dev_priv,
 			  struct bdb_header *bdb)
 {
 	struct sdvo_device_mapping *p_mapping;
-	struct bdb_general_definitions *p_defs;
-	union child_device_config *p_child;
+	const struct bdb_general_definitions *p_defs;
+	const union child_device_config *p_child;
 	int i, child_device_num, count;
 	u16	block_size;
 
@@ -547,7 +548,7 @@ static void
 parse_driver_features(struct drm_i915_private *dev_priv,
 		       struct bdb_header *bdb)
 {
-	struct bdb_driver_features *driver;
+	const struct bdb_driver_features *driver;
 
 	driver = find_section(bdb, BDB_DRIVER_FEATURES);
 	if (!driver)
@@ -573,9 +574,9 @@ parse_driver_features(struct drm_i915_private *dev_priv,
 static void
 parse_edp(struct drm_i915_private *dev_priv, struct bdb_header *bdb)
 {
-	struct bdb_edp *edp;
-	struct edp_power_seq *edp_pps;
-	struct edp_link_params *edp_link_params;
+	const struct bdb_edp *edp;
+	const struct edp_power_seq *edp_pps;
+	const struct edp_link_params *edp_link_params;
 
 	edp = find_section(bdb, BDB_EDP);
 	if (!edp) {
@@ -685,8 +686,8 @@ parse_edp(struct drm_i915_private *dev_priv, struct bdb_header *bdb)
 static void
 parse_psr(struct drm_i915_private *dev_priv, struct bdb_header *bdb)
 {
-	struct bdb_psr *psr;
-	struct psr_table *psr_table;
+	const struct bdb_psr *psr;
+	const struct psr_table *psr_table;
 
 	psr = find_section(bdb, BDB_PSR);
 	if (!psr) {
@@ -796,11 +797,12 @@ static u8 *goto_next_sequence(u8 *data, int *size)
 static void
 parse_mipi(struct drm_i915_private *dev_priv, struct bdb_header *bdb)
 {
-	struct bdb_mipi_config *start;
-	struct bdb_mipi_sequence *sequence;
-	struct mipi_config *config;
-	struct mipi_pps_data *pps;
-	u8 *data, *seq_data;
+	const struct bdb_mipi_config *start;
+	const struct bdb_mipi_sequence *sequence;
+	const struct mipi_config *config;
+	const struct mipi_pps_data *pps;
+	u8 *data;
+	const u8 *seq_data;
 	int i, panel_id, seq_size;
 	u16 block_size;
 
@@ -1068,8 +1070,9 @@ static void
 parse_device_mapping(struct drm_i915_private *dev_priv,
 		       struct bdb_header *bdb)
 {
-	struct bdb_general_definitions *p_defs;
-	union child_device_config *p_child, *child_dev_ptr;
+	const struct bdb_general_definitions *p_defs;
+	const union child_device_config *p_child;
+	union child_device_config *child_dev_ptr;
 	int i, child_device_num, count;
 	u16	block_size;
 
@@ -1126,8 +1129,7 @@ parse_device_mapping(struct drm_i915_private *dev_priv,
 
 		child_dev_ptr = dev_priv->vbt.child_dev + count;
 		count++;
-		memcpy((void *)child_dev_ptr, (void *)p_child,
-					sizeof(*p_child));
+		memcpy(child_dev_ptr, p_child, sizeof(*p_child));
 	}
 	return;
 }