linux-kernel - [PATCH v2] dma: qcom: bam_dma: Manage clocks when controlled

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Date:   Tue, 26 Jan 2021 16:18:59 -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 v2] 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>
---

v1->v2:
	- As per Shawn's suggestion, use devm_clk_get_optional to get the
	  bam clock if the "controlled_remotely" property is set so that
	  the clock code takes care of setting the bam clock to NULL if
	  not specified by dt. 
	- Remove the check for "controlled_remotely" property in
	  bam_dma_resume now that clock enable / disable is based on
	  whether bamclk is NULL or not.
	- Rebased to v5.11-rc5

 drivers/dma/qcom/bam_dma.c | 29 +++++++++++++++--------------
 1 file changed, 15 insertions(+), 14 deletions(-)

diff --git a/drivers/dma/qcom/bam_dma.c b/drivers/dma/qcom/bam_dma.c
index 88579857ca1d..c8a77b428b52 100644
--- a/drivers/dma/qcom/bam_dma.c
+++ b/drivers/dma/qcom/bam_dma.c
@@ -1270,13 +1270,13 @@ static int bam_dma_probe(struct platform_device *pdev)
 			dev_err(bdev->dev, "num-ees unspecified in dt\n");
 	}
 
-	bdev->bamclk = devm_clk_get(bdev->dev, "bam_clk");
-	if (IS_ERR(bdev->bamclk)) {
-		if (!bdev->controlled_remotely)
-			return PTR_ERR(bdev->bamclk);
+	if (bdev->controlled_remotely)
+		bdev->bamclk = devm_clk_get_optional(bdev->dev, "bam_clk");
+	else
+		bdev->bamclk = devm_clk_get(bdev->dev, "bam_clk");
 
-		bdev->bamclk = NULL;
-	}
+	if (IS_ERR(bdev->bamclk))
+		return PTR_ERR(bdev->bamclk);
 
 	ret = clk_prepare_enable(bdev->bamclk);
 	if (ret) {
@@ -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 +1451,13 @@ 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);
+	}
 
 	return 0;
 }
-- 
2.25.1