linux-kernel - [PATCH] clk: qcom: gfm-mux: use runtime pm while accessing registers

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Date:   Tue, 21 Mar 2023 17:57:58 +0000
From:   Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
To:     andersson@...nel.org, agross@...nel.org
Cc:     konrad.dybcio@...aro.org, mturquette@...libre.com,
        sboyd@...nel.org, linux-arm-msm@...r.kernel.org,
        linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org,
        Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
        stable@...r.kernel.org, Amit Pundir <amit.pundir@...aro.org>
Subject: [PATCH] clk: qcom: gfm-mux: use runtime pm while accessing registers

gfm mux driver does support runtime pm but we never use it while
accessing registers. Looks like this driver was getting lucky and
totally depending on other drivers to leave the clk on.

Fix this by doing runtime pm while accessing registers.

Fixes: a2d8f507803e ("clk: qcom: Add support to LPASS AUDIO_CC Glitch Free Mux clocks")
Cc: stable@...r.kernel.org
Reported-by: Amit Pundir <amit.pundir@...aro.org>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
---
 drivers/clk/qcom/lpass-gfm-sm8250.c | 29 ++++++++++++++++++++++++++++-
 1 file changed, 28 insertions(+), 1 deletion(-)

diff --git a/drivers/clk/qcom/lpass-gfm-sm8250.c b/drivers/clk/qcom/lpass-gfm-sm8250.c
index 96f476f24eb2..bcf0ea534f7f 100644
--- a/drivers/clk/qcom/lpass-gfm-sm8250.c
+++ b/drivers/clk/qcom/lpass-gfm-sm8250.c
@@ -38,14 +38,37 @@ struct clk_gfm {
 static u8 clk_gfm_get_parent(struct clk_hw *hw)
 {
 	struct clk_gfm *clk = to_clk_gfm(hw);
+	int ret;
+	u8 parent;
+
+	ret = pm_runtime_resume_and_get(clk->priv->dev);
+	if (ret < 0 && ret != -EACCES) {
+		dev_err_ratelimited(clk->priv->dev,
+				    "pm_runtime_resume_and_get failed in %s, ret %d\n",
+				    __func__, ret);
+		return ret;
+	}
+
+	parent = readl(clk->gfm_mux) & clk->mux_mask;
+
+	pm_runtime_mark_last_busy(clk->priv->dev);
 
-	return readl(clk->gfm_mux) & clk->mux_mask;
+	return parent;
 }
 
 static int clk_gfm_set_parent(struct clk_hw *hw, u8 index)
 {
 	struct clk_gfm *clk = to_clk_gfm(hw);
 	unsigned int val;
+	int ret;
+
+	ret = pm_runtime_resume_and_get(clk->priv->dev);
+	if (ret < 0 && ret != -EACCES) {
+		dev_err_ratelimited(clk->priv->dev,
+				    "pm_runtime_resume_and_get failed in %s, ret %d\n",
+				    __func__, ret);
+		return ret;
+	}
 
 	val = readl(clk->gfm_mux);
 
@@ -57,6 +80,8 @@ static int clk_gfm_set_parent(struct clk_hw *hw, u8 index)
 
 	writel(val, clk->gfm_mux);
 
+	pm_runtime_mark_last_busy(clk->priv->dev);
+
 	return 0;
 }
 
@@ -251,6 +276,8 @@ static int lpass_gfm_clk_driver_probe(struct platform_device *pdev)
 	if (IS_ERR(cc->base))
 		return PTR_ERR(cc->base);
 
+	cc->dev = dev;
+
 	err = devm_pm_runtime_enable(dev);
 	if (err)
 		return err;
-- 
2.21.0