soundwire: bus: test read status

In the existing code we may read a negative error value but still mask
it and write it back.

Make sure all reads are tested and errors not propagated further.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Guennadi Liakhovetski <guennadi.liakhovetski@intel.com>
Reviewed-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>
Reviewed-by: Bard Liao <bard.liao@intel.com>

Author: plbossart

drivers/soundwire/bus.c

@@ -875,8 +875,12 @@ static int sdw_slave_clk_stop_prepare(struct sdw_slave *slave,
 		if (wake_en)
 			val |= SDW_SCP_SYSTEMCTRL_WAKE_UP_EN;
 	} else {
-		val = sdw_read_no_pm(slave, SDW_SCP_SYSTEMCTRL);
-
+		ret = sdw_read_no_pm(slave, SDW_SCP_SYSTEMCTRL);
+		if (ret < 0) {
+			dev_err(&slave->dev, "SDW_SCP_SYSTEMCTRL read failed:%d\n", ret);
+			return ret;
+		}
+		val = ret;
 		val &= ~(SDW_SCP_SYSTEMCTRL_CLK_STP_PREP);
 	}
 
@@ -897,6 +901,10 @@ static int sdw_bus_wait_for_clk_prep_deprep(struct sdw_bus *bus, u16 dev_num)
 	do {
 		val = sdw_bread_no_pm(bus, dev_num, SDW_SCP_STAT) &
 			SDW_SCP_STAT_CLK_STP_NF;
+		if (val < 0) {
+			dev_err(bus->dev, "SDW_SCP_STAT bread failed:%d\n", val);
+			return val;
+		}
 		if (!val) {
 			dev_info(bus->dev, "clock stop prep/de-prep done slave:%d",
 				 dev_num);
@@ -1264,6 +1272,11 @@ static int sdw_initialize_slave(struct sdw_slave *slave)
 	if (slave->bus->prop.quirks & SDW_MASTER_QUIRKS_CLEAR_INITIAL_CLASH) {
 		/* Clear bus clash interrupt before enabling interrupt mask */
 		status = sdw_read_no_pm(slave, SDW_SCP_INT1);
+		if (status < 0) {
+			dev_err(&slave->dev,
+				"SDW_SCP_INT1 read failed:%d\n", status);
+			return status;
+		}
 		if (status & SDW_SCP_INT1_BUS_CLASH) {
 			dev_warn(&slave->dev, "Bus clash detected before INT mask is enabled\n");
 			sdw_write_no_pm(slave, SDW_SCP_INT1, SDW_SCP_INT1_BUS_CLASH);
@@ -1273,6 +1286,11 @@ static int sdw_initialize_slave(struct sdw_slave *slave)
 	    !(slave->prop.quirks & SDW_SLAVE_QUIRKS_INVALID_INITIAL_PARITY)) {
 		/* Clear parity interrupt before enabling interrupt mask */
 		status = sdw_read_no_pm(slave, SDW_SCP_INT1);
+		if (status < 0) {
+			dev_err(&slave->dev,
+				"SDW_SCP_INT1 read failed:%d\n", status);
+			return status;
+		}
 		if (status & SDW_SCP_INT1_PARITY) {
 			dev_warn(&slave->dev, "PARITY error detected before INT mask is enabled\n");
 			sdw_write_no_pm(slave, SDW_SCP_INT1, SDW_SCP_INT1_PARITY);