linux-kernel - [PATCH] drivers: dma: qcom: bam_dma: Manage clocks when controlled

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Date:   Thu, 21 Jan 2021 21:52:51 -0500
From:   Thara Gopinath <thara.gopinath@...aro.org>
To:     agross@...nel.org, bjorn.andersson@...aro.org,
        dan.j.williams@...el.com, vkoul@...nel.org
Cc:     shawn.guo@...aro.org, srinivas.kandagatla@...aro.org,
        linux-arm-msm@...r.kernel.org, dmaengine@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] drivers: dma: qcom: bam_dma: Manage clocks when controlled_remotely is set

When bam dma is "controlled remotely", thus far clocks were not controlled
from the Linux. In this scenario, Linux was disabling runtime pm in bam dma
driver and not doing any clock management in suspend/resume hooks.

With introduction of crypto engine bam dma, the clock is a rpmh resource
that can be controlled from both Linux and TZ/remote side.  Now bam dma
clock is getting enabled during probe even though the bam dma can be
"controlled remotely". But due to clocks not being handled properly,
bam_suspend generates a unbalanced clk_unprepare warning during system
suspend.

To fix the above issue and to enable proper clock-management, this patch
enables runtim-pm and handles bam dma clocks in suspend/resume hooks if
the clock node is present irrespective of controlled_remotely property.

Signed-off-by: Thara Gopinath <thara.gopinath@...aro.org>
---
 drivers/dma/qcom/bam_dma.c | 20 +++++++++++---------
 1 file changed, 11 insertions(+), 9 deletions(-)

diff --git a/drivers/dma/qcom/bam_dma.c b/drivers/dma/qcom/bam_dma.c
index 88579857ca1d..b3a34be63e99 100644
--- a/drivers/dma/qcom/bam_dma.c
+++ b/drivers/dma/qcom/bam_dma.c
@@ -1350,7 +1350,7 @@ static int bam_dma_probe(struct platform_device *pdev)
 	if (ret)
 		goto err_unregister_dma;

-	if (bdev->controlled_remotely) {
+	if (!bdev->bamclk) {
 		pm_runtime_disable(&pdev->dev);
 		return 0;
 	}
@@ -1438,10 +1438,10 @@ static int __maybe_unused bam_dma_suspend(struct device *dev)
 {
 	struct bam_device *bdev = dev_get_drvdata(dev);

-	if (!bdev->controlled_remotely)
+	if (bdev->bamclk) {
 		pm_runtime_force_suspend(dev);
-
-	clk_unprepare(bdev->bamclk);
+		clk_unprepare(bdev->bamclk);
+	}

 	return 0;
 }
@@ -1451,12 +1451,14 @@ static int __maybe_unused bam_dma_resume(struct device *dev)
 	struct bam_device *bdev = dev_get_drvdata(dev);
 	int ret;

-	ret = clk_prepare(bdev->bamclk);
-	if (ret)
-		return ret;
+	if (bdev->bamclk) {
+		ret = clk_prepare(bdev->bamclk);
+		if (ret)
+			return ret;

-	if (!bdev->controlled_remotely)
-		pm_runtime_force_resume(dev);
+		if (!bdev->controlled_remotely)
+			pm_runtime_force_resume(dev);
+	}

 	return 0;
 }
-- 
2.25.1