linux-kernel - [PATCH] soundwire: return earlier if no slave is attached

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Date:   Tue, 26 Jan 2021 16:54:39 +0800
From:   Bard Liao <yung-chuan.liao@...ux.intel.com>
To:     alsa-devel@...a-project.org, vkoul@...nel.org
Cc:     vinod.koul@...aro.org, linux-kernel@...r.kernel.org,
        gregkh@...uxfoundation.org, jank@...ence.com,
        srinivas.kandagatla@...aro.org, rander.wang@...ux.intel.com,
        ranjani.sridharan@...ux.intel.com, hui.wang@...onical.com,
        pierre-louis.bossart@...ux.intel.com, sanyog.r.kale@...el.com,
        bard.liao@...el.com
Subject: [PATCH] soundwire: return earlier if no slave is attached

From: Chao Song <chao.song@...ux.intel.com>

If there is no slave attached to soundwire bus, we
can return earlier from sdw_bus_prep_clk_stop() and
sdw_bus_exit_clk_stop(), this saves a redundant value
check.

Signed-off-by: Chao Song <chao.song@...ux.intel.com>
Reviewed-by: Rander Wang <rander.wang@...el.com>
Reviewed-by: Guennadi Liakhovetski <guennadi.liakhovetski@...ux.intel.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
Signed-off-by: Bard Liao <yung-chuan.liao@...ux.intel.com>
---
 drivers/soundwire/bus.c | 23 ++++++++++-------------
 1 file changed, 10 insertions(+), 13 deletions(-)

diff --git a/drivers/soundwire/bus.c b/drivers/soundwire/bus.c
index 82df088c9333..d9deafdcf495 100644
--- a/drivers/soundwire/bus.c
+++ b/drivers/soundwire/bus.c
@@ -951,17 +951,17 @@ int sdw_bus_prep_clk_stop(struct sdw_bus *bus)
 			simple_clk_stop = false;
 	}
 
-	if (is_slave && !simple_clk_stop) {
+	/* Skip remaining clock stop preparation if no Slave is attached */
+	if (!is_slave)
+		return ret;
+
+	if (!simple_clk_stop) {
 		ret = sdw_bus_wait_for_clk_prep_deprep(bus,
 						       SDW_BROADCAST_DEV_NUM);
 		if (ret < 0)
 			return ret;
 	}
 
-	/* Don't need to inform slaves if there is no slave attached */
-	if (!is_slave)
-		return ret;
-
 	/* Inform slaves that prep is done */
 	list_for_each_entry(slave, &bus->slaves, node) {
 		if (!slave->dev_num)
@@ -1075,16 +1075,13 @@ int sdw_bus_exit_clk_stop(struct sdw_bus *bus)
 				 "clk stop deprep failed:%d", ret);
 	}
 
-	if (is_slave && !simple_clk_stop)
+	/* Skip remaining clock stop de-preparation if no Slave is attached */
+	if (!is_slave)
+		return 0;
+
+	if (!simple_clk_stop)
 		sdw_bus_wait_for_clk_prep_deprep(bus, SDW_BROADCAST_DEV_NUM);
 
-	/*
-	 * Don't need to call slave callback function if there is no slave
-	 * attached
-	 */
-	if (!is_slave)
-		return 0;
-
 	list_for_each_entry(slave, &bus->slaves, node) {
 		if (!slave->dev_num)
 			continue;
-- 
2.17.1