drm/amd/display: Fix detection of aligned DMUB firmware meta info

[Why]
A built firmware binary may be aligned to 16-bytes with padding at the
end as necessary. In the case that padding was applied the meta info
will not be detected correctly and we won't be able to allocate the
appropriate firmware and tracebuffer sizes.

[How]
To maintain compatibility with already released firmware where this
occurs we need to try every meta offset from 0..15 inclusive.

Extract out the meta info checker into a helper function that's called
for each of these offsets and exit early when we've found it.
Reviewed-by: Eric Yang <Eric.Yang2@amd.com>
Acked-by: Anson Jacob <Anson.Jacob@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dmub/src/dmub_srv.c

@@ -100,24 +100,9 @@ void dmub_flush_buffer_mem(const struct dmub_fb *fb)
 }
 
 static const struct dmub_fw_meta_info *
-dmub_get_fw_meta_info(const struct dmub_srv_region_params *params)
+dmub_get_fw_meta_info_from_blob(const uint8_t *blob, uint32_t blob_size, uint32_t meta_offset)
 {
 	const union dmub_fw_meta *meta;
-	const uint8_t *blob = NULL;
-	uint32_t blob_size = 0;
-	uint32_t meta_offset = 0;
-
-	if (params->fw_bss_data && params->bss_data_size) {
-		/* Legacy metadata region. */
-		blob = params->fw_bss_data;
-		blob_size = params->bss_data_size;
-		meta_offset = DMUB_FW_META_OFFSET;
-	} else if (params->fw_inst_const && params->inst_const_size) {
-		/* Combined metadata region. */
-		blob = params->fw_inst_const;
-		blob_size = params->inst_const_size;
-		meta_offset = 0;
-	}
 
 	if (!blob || !blob_size)
 		return NULL;
@@ -134,6 +119,32 @@ dmub_get_fw_meta_info(const struct dmub_srv_region_params *params)
 	return &meta->info;
 }
 
+static const struct dmub_fw_meta_info *
+dmub_get_fw_meta_info(const struct dmub_srv_region_params *params)
+{
+	const struct dmub_fw_meta_info *info = NULL;
+
+	if (params->fw_bss_data && params->bss_data_size) {
+		/* Legacy metadata region. */
+		info = dmub_get_fw_meta_info_from_blob(params->fw_bss_data,
+						       params->bss_data_size,
+						       DMUB_FW_META_OFFSET);
+	} else if (params->fw_inst_const && params->inst_const_size) {
+		/* Combined metadata region - can be aligned to 16-bytes. */
+		uint32_t i;
+
+		for (i = 0; i < 16; ++i) {
+			info = dmub_get_fw_meta_info_from_blob(
+				params->fw_inst_const, params->inst_const_size, i);
+
+			if (info)
+				break;
+		}
+	}
+
+	return info;
+}
+
 static bool dmub_srv_hw_setup(struct dmub_srv *dmub, enum dmub_asic asic)
 {
 	struct dmub_srv_hw_funcs *funcs = &dmub->hw_funcs;