linux-kernel - [PATCH] spi: mediatek: Fix DEVAPC Violation at KO Remove

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Message-ID: <20221110072839.30961-1-zhichao.liu@mediatek.com>
Date:   Thu, 10 Nov 2022 15:28:39 +0800
From:   Zhichao Liu <zhichao.liu@...iatek.com>
To:     Mark Brown <broonie@...nel.org>
CC:     <linux-spi@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-mediatek@...ts.infradead.org>,
        <srv_heupstream@...iatek.com>, <zhichao.liu@...iatek.com>
Subject: [PATCH] spi: mediatek: Fix DEVAPC Violation at KO Remove

A DEVAPC violation occurs when removing the module
due to accessing HW registers without base clock.
To fix this bug, the correct method is:
1. Call the runtime resume function to enable the
   clock;
2. Operate the registers to reset the HW;
3. Turn off the clocks and disable the device
   RPM mechanism.

Signed-off-by: Zhichao Liu <zhichao.liu@...iatek.com>
---
 drivers/spi/spi-mt65xx.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/spi/spi-mt65xx.c b/drivers/spi/spi-mt65xx.c
index a33c9a3de395..d6aff909fc36 100644
--- a/drivers/spi/spi-mt65xx.c
+++ b/drivers/spi/spi-mt65xx.c
@@ -1273,8 +1273,11 @@ static int mtk_spi_remove(struct platform_device *pdev)
 {
 	struct spi_master *master = platform_get_drvdata(pdev);
 	struct mtk_spi *mdata = spi_master_get_devdata(master);
+	int ret;
 
-	pm_runtime_disable(&pdev->dev);
+	ret = pm_runtime_resume_and_get(&pdev->dev);
+	if (ret < 0)
+		return ret;
 
 	mtk_spi_reset(mdata);
 
@@ -1283,6 +1286,9 @@ static int mtk_spi_remove(struct platform_device *pdev)
 		clk_unprepare(mdata->spi_hclk);
 	}
 
+	pm_runtime_put_noidle(&pdev->dev);
+	pm_runtime_disable(&pdev->dev);
+
 	return 0;
 }
 
-- 
2.18.0