soundwire: bus: use quirk to filter out invalid parity errors

If a Slave device reports with a quirk that its initial parity check
may be incorrect, filter it but keep the parity checks active in
steady state.
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Reviewed-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>
Reviewed-by: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>
Link: https://lore.kernel.org/r/20200908134521.6781-5-yung-chuan.liao@linux.intel.comSigned-off-by: Vinod Koul <vkoul@kernel.org>

drivers/soundwire/bus.c

@@ -1362,6 +1362,8 @@ static int sdw_handle_slave_alerts(struct sdw_slave *slave)
 	unsigned long port;
 	bool slave_notify = false;
 	u8 buf, buf2[2], _buf, _buf2[2];
+	bool parity_check;
+	bool parity_quirk;
 
 	sdw_modify_slave_status(slave, SDW_SLAVE_ALERT);
 
@@ -1394,7 +1396,11 @@ static int sdw_handle_slave_alerts(struct sdw_slave *slave)
 		 * interrupt
 		 */
 		if (buf & SDW_SCP_INT1_PARITY) {
-			if (slave->prop.scp_int1_mask & SDW_SCP_INT1_PARITY)
+			parity_check = slave->prop.scp_int1_mask & SDW_SCP_INT1_PARITY;
+			parity_quirk = !slave->first_interrupt_done &&
+				(slave->prop.quirks & SDW_SLAVE_QUIRKS_INVALID_INITIAL_PARITY);
+
+			if (parity_check && !parity_quirk)
 				dev_err(&slave->dev, "Parity error detected\n");
 			clear |= SDW_SCP_INT1_PARITY;
 		}

include/linux/soundwire/sdw.h

@@ -358,6 +358,7 @@ struct sdw_dpn_prop {
  * @src_dpn_prop: Source Data Port N properties
  * @sink_dpn_prop: Sink Data Port N properties
  * @scp_int1_mask: SCP_INT1_MASK desired settings
+ * @quirks: bitmask identifying deltas from the MIPI specification
  */
 struct sdw_slave_prop {
 	u32 mipi_revision;
@@ -380,8 +381,11 @@ struct sdw_slave_prop {
 	struct sdw_dpn_prop *src_dpn_prop;
 	struct sdw_dpn_prop *sink_dpn_prop;
 	u8 scp_int1_mask;
+	u32 quirks;
 };
 
+#define SDW_SLAVE_QUIRKS_INVALID_INITIAL_PARITY	BIT(0)
+
 /**
  * struct sdw_master_prop - Master properties
  * @revision: MIPI spec version of the implementation