linux-kernel - [PATCH] clk: mediatek: mt8183: Only enable runtime PM on mt8183-mfgcfg

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Message-ID: <20240613120357.1043342-1-treapking@chromium.org>
Date: Thu, 13 Jun 2024 20:02:28 +0800
From: Pin-yen Lin <treapking@...omium.org>
To: Michael Turquette <mturquette@...libre.com>,
	Stephen Boyd <sboyd@...nel.org>,
	Matthias Brugger <matthias.bgg@...il.com>,
	AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
Cc: linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	linux-mediatek@...ts.infradead.org,
	Chen-Yu Tsai <wenst@...omium.org>,
	linux-clk@...r.kernel.org,
	Pin-yen Lin <treapking@...omium.org>
Subject: [PATCH] clk: mediatek: mt8183: Only enable runtime PM on mt8183-mfgcfg

Commit 2f7b1d8b5505 ("clk: mediatek: Do a runtime PM get on controllers
during probe") enabled runtime PM for all mediatek clock controllers,
but this introduced an issue on the resume path.

If a device resumes earlier than the clock controller and calls
clk_prepare() when runtime PM is enabled on the controller, it will end
up calling clk_pm_runtime_get(). But the subsequent
pm_runtime_resume_and_get() call will fail because the runtime PM is
temporarily disabled during suspend.

To workaround this, introduce a need_runtime_pm flag and only enable it
on mt8183-mfgcfg, which is the driver that observed deadlock previously.
Hopefully mt8183-cfgcfg won't run into the issue at the resume stage
because the GPU should have stopped rendering before the system calls
suspend.

Fixes: 2f7b1d8b5505 ("clk: mediatek: Do a runtime PM get on controllers during probe")
Signed-off-by: Pin-yen Lin <treapking@...omium.org>

---

 drivers/clk/mediatek/clk-mt8183-mfgcfg.c |  1 +
 drivers/clk/mediatek/clk-mtk.c           | 24 ++++++++++++++----------
 drivers/clk/mediatek/clk-mtk.h           |  2 ++
 3 files changed, 17 insertions(+), 10 deletions(-)

diff --git a/drivers/clk/mediatek/clk-mt8183-mfgcfg.c b/drivers/clk/mediatek/clk-mt8183-mfgcfg.c
index c89c3d58fedc..b1e802bbfaef 100644
--- a/drivers/clk/mediatek/clk-mt8183-mfgcfg.c
+++ b/drivers/clk/mediatek/clk-mt8183-mfgcfg.c
@@ -29,6 +29,7 @@ static const struct mtk_gate mfg_clks[] = {
 static const struct mtk_clk_desc mfg_desc = {
 	.clks = mfg_clks,
 	.num_clks = ARRAY_SIZE(mfg_clks),
+	.need_runtime_pm = true,
 };
 
 static const struct of_device_id of_match_clk_mt8183_mfg[] = {
diff --git a/drivers/clk/mediatek/clk-mtk.c b/drivers/clk/mediatek/clk-mtk.c
index bd37ab4d1a9b..ba1d1c495bc2 100644
--- a/drivers/clk/mediatek/clk-mtk.c
+++ b/drivers/clk/mediatek/clk-mtk.c
@@ -496,14 +496,16 @@ static int __mtk_clk_simple_probe(struct platform_device *pdev,
 	}
 
 
-	devm_pm_runtime_enable(&pdev->dev);
-	/*
-	 * Do a pm_runtime_resume_and_get() to workaround a possible
-	 * deadlock between clk_register() and the genpd framework.
-	 */
-	r = pm_runtime_resume_and_get(&pdev->dev);
-	if (r)
-		return r;
+	if (mcd->need_runtime_pm) {
+		devm_pm_runtime_enable(&pdev->dev);
+		/*
+		 * Do a pm_runtime_resume_and_get() to workaround a possible
+		 * deadlock between clk_register() and the genpd framework.
+		 */
+		r = pm_runtime_resume_and_get(&pdev->dev);
+		if (r)
+			return r;
+	}
 
 	/* Calculate how many clk_hw_onecell_data entries to allocate */
 	num_clks = mcd->num_clks + mcd->num_composite_clks;
@@ -585,7 +587,8 @@ static int __mtk_clk_simple_probe(struct platform_device *pdev,
 			goto unregister_clks;
 	}
 
-	pm_runtime_put(&pdev->dev);
+	if (mcd->need_runtime_pm)
+		pm_runtime_put(&pdev->dev);
 
 	return r;
 
@@ -618,7 +621,8 @@ static int __mtk_clk_simple_probe(struct platform_device *pdev,
 	if (mcd->shared_io && base)
 		iounmap(base);
 
-	pm_runtime_put(&pdev->dev);
+	if (mcd->need_runtime_pm)
+		pm_runtime_put(&pdev->dev);
 	return r;
 }
 
diff --git a/drivers/clk/mediatek/clk-mtk.h b/drivers/clk/mediatek/clk-mtk.h
index 22096501a60a..c17fe1c2d732 100644
--- a/drivers/clk/mediatek/clk-mtk.h
+++ b/drivers/clk/mediatek/clk-mtk.h
@@ -237,6 +237,8 @@ struct mtk_clk_desc {
 
 	int (*clk_notifier_func)(struct device *dev, struct clk *clk);
 	unsigned int mfg_clk_idx;
+
+	bool need_runtime_pm;
 };
 
 int mtk_clk_pdev_probe(struct platform_device *pdev);
-- 
2.45.2.505.gda0bf45e8d-goog