From: Pierre-Louis Bossart <pierre-louis.bossart@xxxxxxxxxxxxxxx>
The Cadence IP can be configured in two different ways to deal with
CMD_IGNORED replies to broadcast commands. The CMD_ACCEPT bitfield
controls whether the command is discarded or if the IP proceeds with
the change (typically a bank switch or clock stop command).
The existing code seems to be inconsistent:
a) For some historical reason, we set this CMD_ACCEPT bitfield during
the initialization, but we don't during a resume from a clock-stoppped
state.
b) In addition, the loop used in the clock-stop sequence is quite
racy, it's possible that a device has lost sync but it's still tagged
as ATTACHED.
c) If somehow a Device loses sync and is unable to ack a broadcast
command, we do not have an error handling mechanism anyways. The IP
should go ahead and let the Device regain sync at a later time.
Make sure the CMD_ACCEPT bit is always set.
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@xxxxxxxxxxxxxxx>
Reviewed-by: Guennadi Liakhovetski <guennadi.liakhovetski@xxxxxxxxxxxxxxx>
Reviewed-by: Rander Wang <rander.wang@xxxxxxxxx>
Signed-off-by: Bard Liao <yung-chuan.liao@xxxxxxxxxxxxxxx>
---
drivers/soundwire/cadence_master.c | 21 ++-------------------
1 file changed, 2 insertions(+), 19 deletions(-)
diff --git a/drivers/soundwire/cadence_master.c b/drivers/soundwire/cadence_master.c
index 192dac10f0c2..25950422b085 100644
--- a/drivers/soundwire/cadence_master.c
+++ b/drivers/soundwire/cadence_master.c
@@ -1428,20 +1428,6 @@ int sdw_cdns_clock_stop(struct sdw_cdns *cdns, bool block_wake)
}
}
- /*
- * This CMD_ACCEPT should be used when there are no devices
- * attached on the link when entering clock stop mode. If this is
- * not set and there is a broadcast write then the command ignored
- * will be treated as a failure
- */
- if (!slave_present)
- cdns_updatel(cdns, CDNS_MCP_CONTROL,
- CDNS_MCP_CONTROL_CMD_ACCEPT,
- CDNS_MCP_CONTROL_CMD_ACCEPT);
- else
- cdns_updatel(cdns, CDNS_MCP_CONTROL,
- CDNS_MCP_CONTROL_CMD_ACCEPT, 0);
-
/* commit changes */
ret = cdns_config_update(cdns);
if (ret < 0) {
@@ -1508,11 +1494,8 @@ int sdw_cdns_clock_restart(struct sdw_cdns *cdns, bool bus_reset)
cdns_updatel(cdns, CDNS_MCP_CONTROL,
CDNS_MCP_CONTROL_BLOCK_WAKEUP, 0);
- /*
- * clear CMD_ACCEPT so that the command ignored
- * will be treated as a failure during a broadcast write
- */
- cdns_updatel(cdns, CDNS_MCP_CONTROL, CDNS_MCP_CONTROL_CMD_ACCEPT, 0);
+ cdns_updatel(cdns, CDNS_MCP_CONTROL, CDNS_MCP_CONTROL_CMD_ACCEPT,
+ CDNS_MCP_CONTROL_CMD_ACCEPT);
if (!bus_reset) {
--
2.17.1
