Re: [PATCH v2 1/2] dmaengine: qcom: bam_dma: Take a PM ref at remove()

[Frank Li <Frank.li@oss.nxp.com>]

On Fri, Oct 23, 2026 at 10:15:35AM +0000, Mostafa Saleh wrote:
> 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@google.com>

Reviewed-by: Frank Li <Frank.Li@nxp.com>

> ---
>  drivers/dma/qcom/bam_dma.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/dma/qcom/bam_dma.c b/drivers/dma/qcom/bam_dma.c
> index f67a93a37d48..8a1f4e5d24d1 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 +1426,8 @@ static void bam_dma_remove(struct platform_device *pdev)
>
>  	tasklet_kill(&bdev->task);
>
> +	pm_runtime_disable(&pdev->dev);
> +	pm_runtime_put_noidle(&pdev->dev);
>  	clk_disable_unprepare(bdev->bamclk);
>  }
>
> --
> 2.56.0.307.g5fe7bd680c-goog
>