soundwire: bus: add bra_w/r_threshold

We need a threshold to use BRA. The threshold can be set in the bus
struct when sdw_bus_master_add() is called.

Signed-off-by: Bard Liao <yung-chuan.liao@linux.intel.com>

Author: bardliao

drivers/soundwire/bus.c

@@ -13,6 +13,9 @@
 #include "irq.h"
 #include "sysfs_local.h"
 
+#define DEFAULT_BRA_WRITE_THRESHOLD	800
+#define DEFAULT_BRA_READ_THRESHOLD	400
+
 static DEFINE_IDA(sdw_bus_ida);
 
 static int sdw_get_id(struct sdw_bus *bus)
@@ -163,6 +166,11 @@ int sdw_bus_master_add(struct sdw_bus *bus, struct device *parent,
 	bus->params.curr_bank = SDW_BANK0;
 	bus->params.next_bank = SDW_BANK1;
 
+	if (!bus->bra_w_threshold)
+		bus->bra_w_threshold = DEFAULT_BRA_WRITE_THRESHOLD;
+	if (!bus->bra_r_threshold)
+		bus->bra_r_threshold = DEFAULT_BRA_READ_THRESHOLD;
+
 	return 0;
 }
 EXPORT_SYMBOL(sdw_bus_master_add);

include/linux/soundwire/sdw.h

@@ -1028,6 +1028,10 @@ struct sdw_stream_runtime {
  * are supported. This flag is populated by drivers after reading
  * appropriate firmware (ACPI/DT).
  * @lane_used_bandwidth: how much bandwidth in bits per second is used by each lane
+ * @bra_w_threshold: Message-size threshold (bytes) above which BRA write is used.
+ * If set to 0, a default is used.
+ * @bra_r_threshold: Message-size threshold (bytes) above which BRA read is used.
+ * If set to 0, a default is used.
  */
 struct sdw_bus {
 	struct device *dev;
@@ -1063,6 +1067,8 @@ struct sdw_bus {
 #endif
 	bool multi_link;
 	unsigned int lane_used_bandwidth[SDW_MAX_LANES];
+	unsigned int bra_w_threshold;
+	unsigned int bra_r_threshold;
 };
 
 struct sdw_stream_runtime *sdw_alloc_stream(const char *stream_name, enum sdw_stream_type type);