[PATCH v8] net: airoha: npu: use cacheline-sized buffers for mailbox DMA

[Jakub Kicinski]

On Tue, 18 Aug 2026 08:23:33 +0200 Daniel Pawlik wrote:
> v8 does not switch to coherent DMA; it only rounds up mailbox payload
> allocations (dma_get_cache_alignment() in v9) and maps the same rounded
> length with DMA_BIDIRECTIONAL, while the mailbox length register still
> uses the original payload size. On this board, mapping only the payload
> size regresses probe back to 0.0 even with the larger allocation, so the
> rounded map length seems required here.

Please trace into the dma API implementation on this platform where the
alignment makes a difference. The "unaligned length" path must be buggy.
We should fix it there, not in all the drivers (my concern being that
this is not the only driver that hits the issue).