Re: [PATCH v2 4/5] dt-bindings: dma: sun50i-a64-dma: Add allwinner,sun60i-a733-dma compatible string

[sashiko-bot@kernel.org]

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

Pre-existing issues:
- [High] The IRQ handler loop skips trailing DMA channels if the total number of physical channels is not an exact multiple of the channels per register.
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commit 1a8550cc9da2ef939f555f682f0d5ea9606e1907
Author: Yuanshen Cao <alex.caoys@gmail.com>

dt-bindings: dma: sun50i-a64-dma: Add allwinner,sun60i-a733-dma compatible string

Add `allwinner,sun60i-a733-dma` to the list of compatible strings for the
`sun50i-a64-dma` dtbinding documentation.

>     While the A733 DMA controller shares many similarities with the sun50i-a64
>     DMA controller, it requires a specific configuration due to differences in:
>     - Interrupt register layout and mapping.
>     - Number of channels per interrupt register.

[Severity: High]
This isn't a bug introduced by this patch, but could this truncating
integer division skip trailing DMA channels if the total number of physical
channels is not an exact multiple of the channels per register?

In drivers/dma/sun6i-dma.c:sun6i_dma_interrupt(), the loop condition
determines which interrupt registers to poll:

    for (i = 0; i < sdev->num_pchans / sdev->cfg->num_channels_per_reg; i++) {

For a controller with 12 physical channels (e.g., sun8i_h3_dma_cfg sets
nr_max_channels = 12) and 8 channels per register, 12 / 8 evaluates to 1.

Consequently, the loop only iterates once (for i=0), checking interrupts
for the first 8 channels and completely ignoring the remaining 4 channels.
Any DMA transfers on channels 8-11 will never have their completion
interrupts handled, leading to system hangs or driver timeouts.

Could this be updated to use DIV_ROUND_UP() to ensure all applicable
interrupt registers are processed?

>     - Support for higher (32G) address widths in LLI parameters.
>     
>     Signed-off-by: Yuanshen Cao <alex.caoys@gmail.com>

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Sashiko AI review · https://sashiko.dev/#/patchset/20260621-sun60i-a733-dma-v2-0-340f205891cc@gmail.com?part=4