linux-kernel - [PATCH 1/2] soundwire: qcom: fix unbalanced pm_runtime

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Date:   Wed, 17 May 2023 18:37:49 +0200
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Vinod Koul <vkoul@...nel.org>,
        Bard Liao <yung-chuan.liao@...ux.intel.com>,
        Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>,
        Sanyog Kale <sanyog.r.kale@...el.com>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        Péter Ujfalusi <peter.ujfalusi@...ux.intel.com>,
        Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
        Charles Keepax <ckeepax@...nsource.cirrus.com>,
        alsa-devel@...a-project.org, linux-kernel@...r.kernel.org,
        linux-arm-msm@...r.kernel.org
Cc:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
Subject: [PATCH 1/2] soundwire: qcom: fix unbalanced pm_runtime_put()

This reverts commit 57ed510b0547 ("soundwire: qcom: use
pm_runtime_resume_and_get()") which introduced unbalanced
pm_runtime_put(), when device did not have runtime PM enabled.

If pm_runtime_resume_and_get() failed with -EACCES, the driver continued
execution and finally called pm_runtime_put_autosuspend().  Since
pm_runtime_resume_and_get() drops the usage counter on every error, this
lead to double decrement of that counter visible in certain debugfs
actions on unattached devices (still in reset state):

  $ cat /sys/kernel/debug/soundwire/master-0-0/sdw:0:0217:f001:00:0/registers
  qcom-soundwire 3210000.soundwire-controller: swrm_wait_for_wr_fifo_avail err write overflow
  soundwire sdw-master-0: trf on Slave 1 failed:-5 read addr e36 count 1
  soundwire sdw:0:0217:f001:00:0: Runtime PM usage count underflow!

Fixes: 57ed510b0547 ("soundwire: qcom: use pm_runtime_resume_and_get()")
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
---
 drivers/soundwire/qcom.c | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/drivers/soundwire/qcom.c b/drivers/soundwire/qcom.c
index aad5942e5980..f442280af9d3 100644
--- a/drivers/soundwire/qcom.c
+++ b/drivers/soundwire/qcom.c
@@ -614,11 +614,12 @@ static irqreturn_t qcom_swrm_wake_irq_handler(int irq, void *dev_id)
 	struct qcom_swrm_ctrl *ctrl = dev_id;
 	int ret;
 
-	ret = pm_runtime_resume_and_get(ctrl->dev);
+	ret = pm_runtime_get_sync(ctrl->dev);
 	if (ret < 0 && ret != -EACCES) {
 		dev_err_ratelimited(ctrl->dev,
-				    "pm_runtime_resume_and_get failed in %s, ret %d\n",
+				    "pm_runtime_get_sync failed in %s, ret %d\n",
 				    __func__, ret);
+		pm_runtime_put_noidle(ctrl->dev);
 		return ret;
 	}
 
@@ -1197,11 +1198,12 @@ static int qcom_swrm_startup(struct snd_pcm_substream *substream,
 	struct snd_soc_dai *codec_dai;
 	int ret, i;
 
-	ret = pm_runtime_resume_and_get(ctrl->dev);
+	ret = pm_runtime_get_sync(ctrl->dev);
 	if (ret < 0 && ret != -EACCES) {
 		dev_err_ratelimited(ctrl->dev,
-				    "pm_runtime_resume_and_get failed in %s, ret %d\n",
+				    "pm_runtime_get_sync failed in %s, ret %d\n",
 				    __func__, ret);
+		pm_runtime_put_noidle(ctrl->dev);
 		return ret;
 	}
 
@@ -1402,11 +1404,12 @@ static int swrm_reg_show(struct seq_file *s_file, void *data)
 	struct qcom_swrm_ctrl *ctrl = s_file->private;
 	int reg, reg_val, ret;
 
-	ret = pm_runtime_resume_and_get(ctrl->dev);
+	ret = pm_runtime_get_sync(ctrl->dev);
 	if (ret < 0 && ret != -EACCES) {
 		dev_err_ratelimited(ctrl->dev,
-				    "pm_runtime_resume_and_get failed in %s, ret %d\n",
+				    "pm_runtime_get_sync failed in %s, ret %d\n",
 				    __func__, ret);
+		pm_runtime_put_noidle(ctrl->dev);
 		return ret;
 	}
 
-- 
2.34.1