soundwire: don't program SDW_SCP_BUSCLOCK_SCALE on a unattached Peripheral

The SDW_SCP_BUSCLOCK_SCALE register will be programmed when the
Peripheral is attached. We can and should skip programming the
SDW_SCP_BUSCLOCK_SCALE register when the Peripheral is unattached.

Fixes: 645291c ("Soundwire: stream: program BUSCLOCK_SCALE")
Signed-off-by: Bard Liao <yung-chuan.liao@linux.intel.com>

Author: bardliao

drivers/soundwire/stream.c

@@ -705,6 +705,13 @@ static int sdw_program_params(struct sdw_bus *bus, bool prepare)
 		if (scale_index < 0)
 			return scale_index;
 
+		/* Skip the unattached Peripherals */
+		if (!completion_done(&slave->enumeration_complete)) {
+			dev_warn(&slave->dev,
+				 "Not enumerated, skip programming BUSCLOCK_SCALE\n");
+			continue;
+		}
+
 		ret = sdw_write_no_pm(slave, addr1, scale_index);
 		if (ret < 0) {
 			dev_err(&slave->dev, "SDW_SCP_BUSCLOCK_SCALE register write failed\n");