Re: [PATCH v23 05/14] dmaengine: qcom: bam_dma: Add pipe_lock_supported flag support

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:

Pre-existing issues:
- [High] Unclocked BAM register access in bam_dma_remove() causes system crash.
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--- Patch [5]: [PATCH v23 05/14] dmaengine: qcom: bam_dma: Add pipe_lock_supported flag support ---
commit 52e9e906437f52a7f85afb39e2221eefc5535d38
Author: Bartosz Golaszewski <brgl@kernel.org>

dmaengine: qcom: bam_dma: Add pipe_lock_supported flag support

This commit extends the device match data with a flag indicating whether
the IP supports the BAM lock/unlock feature. It sets this flag to true
on BAM IP versions 1.4.0 and above.

> diff --git a/drivers/dma/qcom/bam_dma.c b/drivers/dma/qcom/bam_dma.c
> index 8ce0fe085c5fe..f3e713a5259c2 100644
> --- a/drivers/dma/qcom/bam_dma.c
> +++ b/drivers/dma/qcom/bam_dma.c

[ ... ]

[Severity: High]
This isn't a bug introduced by this patch, but I noticed a potential system
crash during the device unbind or module unload path in this file:

drivers/dma/qcom/bam_dma.c:bam_dma_remove() {
	...
	pm_runtime_force_suspend(&pdev->dev);

	of_dma_controller_free(pdev->dev.of_node);
	dma_async_device_unregister(&bdev->common);

	/* mask all interrupts for this execution environment */
	writel_relaxed(0, bam_addr(bdev, 0,  BAM_IRQ_SRCS_MSK_EE));

	for (i = 0; i < bdev->num_channels; i++) {
		bam_dma_terminate_all(&bdev->channels[i].vc.chan);
	...
}

Does this sequence trigger a synchronous external abort on ARM architectures?

The call to pm_runtime_force_suspend() shuts off the BAM device clock, but
the function then proceeds to execute unclocked hardware register writes via
writel_relaxed() and indirectly through bam_dma_terminate_all().

Can this hardware safely handle register accesses after its clock has been
disabled, or will this crash the system during teardown?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260721-qcom-qce-cmd-descr-v23-0-1be02deffda9@oss.qualcomm.com?part=5