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

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

[Zhichao Liu]

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@mediatek.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

Re: [PATCH] spi: mediatek: Fix DEVAPC Violation at KO Remove

[AngeloGioacchino Del Regno]

Il 10/11/22 08:28, Zhichao Liu ha scritto:
> 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@mediatek.com>

Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>

Re: [PATCH] spi: mediatek: Fix DEVAPC Violation at KO Remove

[Mark Brown]

On Thu, 10 Nov 2022 15:28:39 +0800, Zhichao Liu wrote:
> 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.
> 
> [...]

Applied to

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi.git for-next

Thanks!

[1/1] spi: mediatek: Fix DEVAPC Violation at KO Remove
      commit: 0d10e90cee9eb57882b0f7e19fd699033722e226

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark