linux-kernel - [PATCH 6/7] soundwire: bus: fix confusion on device used by pm

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Message-Id: <20201202204645.23891-7-yung-chuan.liao@linux.intel.com>
Date:   Thu,  3 Dec 2020 04:46:44 +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,
        bard.liao@...el.com
Subject: [PATCH 6/7] soundwire: bus: fix confusion on device used by pm_runtime

From: Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>

Intel stress-tests routinely report IO timeouts and invalid power
management transitions. Upon further analysis, we seem to be using the
wrong devices in pm_runtime calls.

Before reading and writing registers, we first need to make sure the
Slave is fully resumed. The existing code attempts to do such that,
however because of a confusion dating from 2017 and copy/paste, we
end-up resuming the parent only instead of resuming the codec device.

This can lead to accesses to the Slave registers while the bus is
still being configured and the Slave not enumerated, and as a result
IO errors occur.

This is a classic problem, similar confusions happened for HDaudio
between bus and codec device, leading to power management issues.

Fix by using the relevant device for all uses of pm_runtime functions.

Fixes: 60ee9be255712 ('soundwire: bus: add PM/no-PM versions of read/write functions')
Fixes: aa79293517b39 ('soundwire: bus: fix io error when processing alert event')
Fixes: 9d715fa005ebc ('soundwire: Add IO transfer')
Reported-by: Bard Liao <yung-chuan.liao@...ux.intel.com>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
Reviewed-by: Rander Wang <rander.wang@...ux.intel.com>
Signed-off-by: Bard Liao <yung-chuan.liao@...ux.intel.com>
---
 drivers/soundwire/bus.c | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/drivers/soundwire/bus.c b/drivers/soundwire/bus.c
index c5ea59673dee..c317f41eba4e 100644
--- a/drivers/soundwire/bus.c
+++ b/drivers/soundwire/bus.c
@@ -514,16 +514,16 @@ int sdw_nread(struct sdw_slave *slave, u32 addr, size_t count, u8 *val)
 {
 	int ret;
 
-	ret = pm_runtime_get_sync(slave->bus->dev);
+	ret = pm_runtime_get_sync(&slave->dev);
 	if (ret < 0 && ret != -EACCES) {
-		pm_runtime_put_noidle(slave->bus->dev);
+		pm_runtime_put_noidle(&slave->dev);
 		return ret;
 	}
 
 	ret = sdw_nread_no_pm(slave, addr, count, val);
 
-	pm_runtime_mark_last_busy(slave->bus->dev);
-	pm_runtime_put(slave->bus->dev);
+	pm_runtime_mark_last_busy(&slave->dev);
+	pm_runtime_put(&slave->dev);
 
 	return ret;
 }
@@ -540,16 +540,16 @@ int sdw_nwrite(struct sdw_slave *slave, u32 addr, size_t count, u8 *val)
 {
 	int ret;
 
-	ret = pm_runtime_get_sync(slave->bus->dev);
+	ret = pm_runtime_get_sync(&slave->dev);
 	if (ret < 0 && ret != -EACCES) {
-		pm_runtime_put_noidle(slave->bus->dev);
+		pm_runtime_put_noidle(&slave->dev);
 		return ret;
 	}
 
 	ret = sdw_nwrite_no_pm(slave, addr, count, val);
 
-	pm_runtime_mark_last_busy(slave->bus->dev);
-	pm_runtime_put(slave->bus->dev);
+	pm_runtime_mark_last_busy(&slave->dev);
+	pm_runtime_put(&slave->dev);
 
 	return ret;
 }
@@ -1454,7 +1454,7 @@ static int sdw_handle_slave_alerts(struct sdw_slave *slave)
 	ret = pm_runtime_get_sync(&slave->dev);
 	if (ret < 0 && ret != -EACCES) {
 		dev_err(&slave->dev, "Failed to resume device: %d\n", ret);
-		pm_runtime_put_noidle(slave->bus->dev);
+		pm_runtime_put_noidle(&slave->dev);
 		return ret;
 	}
 
-- 
2.17.1