linux-kernel - [PATCH] soundwire: stream: only change state if needed

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Date:   Tue, 17 Mar 2020 05:51:42 -0500
From:   Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
To:     alsa-devel@...a-project.org
Cc:     linux-kernel@...r.kernel.org, tiwai@...e.de, broonie@...nel.org,
        vkoul@...nel.org, gregkh@...uxfoundation.org, jank@...ence.com,
        srinivas.kandagatla@...aro.org, slawomir.blauciak@...el.com,
        Bard liao <yung-chuan.liao@...ux.intel.com>,
        Rander Wang <rander.wang@...ux.intel.com>,
        Ranjani Sridharan <ranjani.sridharan@...ux.intel.com>,
        Hui Wang <hui.wang@...onical.com>,
        Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>,
        Sanyog Kale <sanyog.r.kale@...el.com>
Subject: [PATCH] soundwire: stream: only change state if needed

In a multi-cpu DAI context, the stream routines may be called from
multiple DAI callbacks. Make sure the stream state only changes for
the first call, and don't return error messages if the target state is
already reached.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
---
 drivers/soundwire/stream.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/drivers/soundwire/stream.c b/drivers/soundwire/stream.c
index 1b43d03c79ea..3319121cd706 100644
--- a/drivers/soundwire/stream.c
+++ b/drivers/soundwire/stream.c
@@ -1572,6 +1572,7 @@ int sdw_prepare_stream(struct sdw_stream_runtime *stream)
 	sdw_acquire_bus_lock(stream);
 
 	if (stream->state == SDW_STREAM_PREPARED) {
+		/* nothing to do */
 		ret = 0;
 		goto state_err;
 	}
@@ -1661,6 +1662,12 @@ int sdw_enable_stream(struct sdw_stream_runtime *stream)
 
 	sdw_acquire_bus_lock(stream);
 
+	if (stream->state == SDW_STREAM_ENABLED) {
+		/* nothing to do */
+		ret = 0;
+		goto state_err;
+	}
+
 	if (stream->state != SDW_STREAM_PREPARED &&
 	    stream->state != SDW_STREAM_DISABLED) {
 		pr_err("%s: %s: inconsistent state state %d\n",
@@ -1744,6 +1751,12 @@ int sdw_disable_stream(struct sdw_stream_runtime *stream)
 
 	sdw_acquire_bus_lock(stream);
 
+	if (stream->state == SDW_STREAM_DISABLED) {
+		/* nothing to do */
+		ret = 0;
+		goto state_err;
+	}
+
 	if (stream->state != SDW_STREAM_ENABLED) {
 		pr_err("%s: %s: inconsistent state state %d\n",
 		       __func__, stream->name, stream->state);
@@ -1809,6 +1822,12 @@ int sdw_deprepare_stream(struct sdw_stream_runtime *stream)
 
 	sdw_acquire_bus_lock(stream);
 
+	if (stream->state == SDW_STREAM_DEPREPARED) {
+		/* nothing to do */
+		ret = 0;
+		goto state_err;
+	}
+
 	if (stream->state != SDW_STREAM_PREPARED &&
 	    stream->state != SDW_STREAM_DISABLED) {
 		pr_err("%s: %s: inconsistent state state %d\n",
-- 
2.20.1