Re: [PATCH 1/2] dmaengine: qcom: bam_dma: Take a PM ref at remove()

[Frank Li]

On Tue, Oct 20, 2026 at 06:08:02PM +0000, Mostafa Saleh wrote:
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>
> bam_dma_remove() calls pm_runtime_dont_use_autosuspend() and
> pm_runtime_force_suspend(), which on a BAM with its own clock disables
> bam_clk, and only then writes BAM_IRQ_SRCS_MSK_EE and terminates the
> channels, touching registers of a block whose clock has just been
> removed, causing the board to reset.
>
> Sashiko(Locally) also reports, it then calls clk_disable_unprepare()
> on a clock that runtime suspend already disabled, which can trigger
> "already disabled" warning in clk_core_disable().
>
> Hold a runtime PM reference across the register accesses and the
> channel teardown. Once the hardware is quiet, disable runtime PM with
> the device still active and drop the clock exactly once, balancing the
> clk_prepare_enable() in probe.
>
> Fixes: 7d2545599f5b ("dmaengine: qcom-bam-dma: Add pm_runtime support")
> Signed-off-by: Mostafa Saleh <smostafa@xxxxxxxxxx>
> ---
>  drivers/dma/qcom/bam_dma.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/dma/qcom/bam_dma.c b/drivers/dma/qcom/bam_dma.c
> index f67a93a37d48..bd583f78e0c1 100644
> --- a/drivers/dma/qcom/bam_dma.c
> +++ b/drivers/dma/qcom/bam_dma.c
> @@ -1403,12 +1403,10 @@ static void bam_dma_remove(struct platform_device *pdev)
>         struct bam_device *bdev = platform_get_drvdata(pdev);
>         u32 i;
>
> -       pm_runtime_dont_use_autosuspend(&pdev->dev);
> -       pm_runtime_force_suspend(&pdev->dev);
> -
>         of_dma_controller_free(pdev->dev.of_node);
>         dma_async_device_unregister(&bdev->common);
>
> +       pm_runtime_get_sync(&pdev->dev);
>         /* mask all interrupts for this execution environment */
>         writel_relaxed(0, bam_addr(bdev, 0,  BAM_IRQ_SRCS_MSK_EE));
>
> @@ -1428,6 +1426,9 @@ static void bam_dma_remove(struct platform_device *pdev)
>
>         tasklet_kill(&bdev->task);
>
> +       pm_runtime_dont_use_autosuspend(&pdev->dev);

After

commit d1706f9da9f40dffe8621cc0ee03b847f41f1d6d
Author: Joshua Crofts <joshua.crofts1@xxxxxxxxx>
Date:   Sat Sep 19 10:24:28 2026 +0200

    PM: runtime: call pm_runtime_dont_use_autosuspend() on reinit()

    Add a pm_runtime_dont_use_autosuspend() call to pm_runtime_reinit() to
    ensure autosuspend is disabled on driver teardown.

    Suggested-by: Frank Li <Frank.Li@xxxxxxx>
    Signed-off-by: Joshua Crofts <joshua.crofts1@xxxxxxxxx>
    Link: https://patch.msgid.link/20260919-move-dont-use-autosuspend-v1-1-f6e2d1315c23@xxxxxxxxx
    Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>


Needn't call pm_runtime_dont_use_autosuspend()


> +       pm_runtime_disable(&pdev->dev);

Can you use devm_pm_*() call to fix this problem.

Frank
> +       pm_runtime_put_noidle(&pdev->dev);
>         clk_disable_unprepare(bdev->bamclk);
>  }
>
> --
> 2.56.0.212.g129ede20d9-goog
>