* [RESEND PATCH] soundwire: cadence_master: always set CMD_ACCEPT
@ 2021-05-11 2:52 Bard Liao
2021-05-11 12:22 ` Vinod Koul
0 siblings, 1 reply; 2+ messages in thread
From: Bard Liao @ 2021-05-11 2:52 UTC (permalink / raw)
To: alsa-devel, vkoul
Cc: vinod.koul, linux-kernel, gregkh, srinivas.kandagatla,
rander.wang, hui.wang, pierre-louis.bossart, sanyog.r.kale,
bard.liao
From: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
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@linux.intel.com>
Reviewed-by: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>
Reviewed-by: Rander Wang <rander.wang@intel.com>
Signed-off-by: Bard Liao <yung-chuan.liao@linux.intel.com>
---
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
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [RESEND PATCH] soundwire: cadence_master: always set CMD_ACCEPT
2021-05-11 2:52 [RESEND PATCH] soundwire: cadence_master: always set CMD_ACCEPT Bard Liao
@ 2021-05-11 12:22 ` Vinod Koul
0 siblings, 0 replies; 2+ messages in thread
From: Vinod Koul @ 2021-05-11 12:22 UTC (permalink / raw)
To: Bard Liao
Cc: alsa-devel, linux-kernel, gregkh, srinivas.kandagatla,
rander.wang, hui.wang, pierre-louis.bossart, sanyog.r.kale,
bard.liao
On 11-05-21, 10:52, Bard Liao wrote:
> From: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
>
> 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.
Applied, thanks
--
~Vinod
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