linux-kernel - [PATCH AUTOSEL 6.0 17/39] spi: mediatek: Fix DEVAPC Violation at KO Remove

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Date:   Mon, 28 Nov 2022 12:35:57 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Zhichao Liu <zhichao.liu@...iatek.com>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>,
        Mark Brown <broonie@...nel.org>,
        Sasha Levin <sashal@...nel.org>, matthias.bgg@...il.com,
        linux-spi@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org
Subject: [PATCH AUTOSEL 6.0 17/39] spi: mediatek: Fix DEVAPC Violation at KO Remove

From: Zhichao Liu <zhichao.liu@...iatek.com>

[ Upstream commit 0d10e90cee9eb57882b0f7e19fd699033722e226 ]

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>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
Link: https://lore.kernel.org/r/20221110072839.30961-1-zhichao.liu@mediatek.com
Signed-off-by: Mark Brown <broonie@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 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 cd9dc358d396..a7cc96aeb590 100644
--- a/drivers/spi/spi-mt65xx.c
+++ b/drivers/spi/spi-mt65xx.c
@@ -1268,8 +1268,11 @@ 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);
 
@@ -1278,6 +1281,9 @@ 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;
 }
 
-- 
2.35.1