linux-kernel - [PATCH] soundwire: bus: clock_stop: don't deal with UNATTACHED Slave devices

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Date:   Sun, 31 May 2020 23:18:06 +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, tiwai@...e.de,
        broonie@...nel.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,
        slawomir.blauciak@...el.com, mengdong.lin@...el.com,
        bard.liao@...el.com
Subject: [PATCH] soundwire: bus: clock_stop: don't deal with UNATTACHED Slave devices

We don't need to do anything for the slave if it is unattached during
clock stop prepare and exit sequences.

Signed-off-by: Bard Liao <yung-chuan.liao@...ux.intel.com>
---
 drivers/soundwire/bus.c | 23 +++++++++++++++++------
 1 file changed, 17 insertions(+), 6 deletions(-)

diff --git a/drivers/soundwire/bus.c b/drivers/soundwire/bus.c
index 2289c2ac8c5a..405335fb790a 100644
--- a/drivers/soundwire/bus.c
+++ b/drivers/soundwire/bus.c
@@ -863,13 +863,13 @@ int sdw_bus_prep_clk_stop(struct sdw_bus *bus)
 		if (!slave->dev_num)
 			continue;
 
-		/* Identify if Slave(s) are available on Bus */
-		is_slave = true;
-
 		if (slave->status != SDW_SLAVE_ATTACHED &&
 		    slave->status != SDW_SLAVE_ALERT)
 			continue;
 
+		/* Identify if Slave(s) are available on Bus */
+		is_slave = true;
+
 		slave_mode = sdw_get_clk_stop_mode(slave);
 		slave->curr_clk_stop_mode = slave_mode;
 
@@ -900,6 +900,10 @@ int sdw_bus_prep_clk_stop(struct sdw_bus *bus)
 			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)
@@ -985,13 +989,13 @@ int sdw_bus_exit_clk_stop(struct sdw_bus *bus)
 		if (!slave->dev_num)
 			continue;
 
-		/* Identify if Slave(s) are available on Bus */
-		is_slave = true;
-
 		if (slave->status != SDW_SLAVE_ATTACHED &&
 		    slave->status != SDW_SLAVE_ALERT)
 			continue;
 
+		/* Identify if Slave(s) are available on Bus */
+		is_slave = true;
+
 		mode = slave->curr_clk_stop_mode;
 
 		if (mode == SDW_CLK_STOP_MODE1) {
@@ -1016,6 +1020,13 @@ int sdw_bus_exit_clk_stop(struct sdw_bus *bus)
 	if (is_slave && !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