[PATCH v2 2/2] soundwire: enable optional clock registers for SoundWire 1.2 devices

[Bard Liao]

From: Pierre-Louis Bossart <pierre-louis.bossart@xxxxxxxxxxxxxxx>

The bus supports the mandatory clock registers for SDCA devices, these
registers can also be optionally supported by SoundWire 1.2 devices
that don't follow the SDCA class specification.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@xxxxxxxxxxxxxxx>
Reviewed-by: Rander Wang <rander.wang@xxxxxxxxx>
Reviewed-by: Péter Ujfalusi <peter.ujfalusi@xxxxxxxxxxxxxxx>
Signed-off-by: Bard Liao <yung-chuan.liao@xxxxxxxxxxxxxxx>
---
 drivers/soundwire/bus.c       | 7 ++++---
 include/linux/soundwire/sdw.h | 4 ++++
 2 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/drivers/soundwire/bus.c b/drivers/soundwire/bus.c
index c23275b443ac..55d393247a0f 100644
--- a/drivers/soundwire/bus.c
+++ b/drivers/soundwire/bus.c
@@ -1233,10 +1233,11 @@ static int sdw_slave_set_frequency(struct sdw_slave *slave)
 
 	/*
 	 * frequency base and scale registers are required for SDCA
-	 * devices. They may also be used for 1.2+/non-SDCA devices,
-	 * but we will need a DisCo property to cover this case
+	 * devices. They may also be used for 1.2+/non-SDCA devices.
+	 * Driver can set the property, we will need a DisCo property
+	 * to discover this case from platform firmware.
 	 */
-	if (!slave->id.class_id)
+	if (!slave->id.class_id && !slave->prop.clock_reg_supported)
 		return 0;
 
 	if (!mclk_freq) {
diff --git a/include/linux/soundwire/sdw.h b/include/linux/soundwire/sdw.h
index 8fb458931772..9a49263c53cf 100644
--- a/include/linux/soundwire/sdw.h
+++ b/include/linux/soundwire/sdw.h
@@ -365,6 +365,9 @@ struct sdw_dpn_prop {
  * @sink_dpn_prop: Sink Data Port N properties
  * @scp_int1_mask: SCP_INT1_MASK desired settings
  * @quirks: bitmask identifying deltas from the MIPI specification
+ * @clock_reg_supported: the Peripheral implements the clock base and scale
+ * registers introduced with the SoundWire 1.2 specification. SDCA devices
+ * do not need to set this boolean property as the registers are required.
  */
 struct sdw_slave_prop {
 	u32 mipi_revision;
@@ -388,6 +391,7 @@ struct sdw_slave_prop {
 	struct sdw_dpn_prop *sink_dpn_prop;
 	u8 scp_int1_mask;
 	u32 quirks;
+	bool clock_reg_supported;
 };
 
 #define SDW_SLAVE_QUIRKS_INVALID_INITIAL_PARITY	BIT(0)
-- 
2.25.1