Re: [PATCH net-next 07/12] net: stmmac: dwxgmac2: export symbols for XGMAC 3.01a DMA

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] Bypassing standard DMA address translation via custom op-table overrides.
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commit 6c8a6ba67e29de7e71f5090bcca63c458ee9639d
Author: Daniel Thompson <daniel@riscstar.com>

net: stmmac: dwxgmac2: export symbols for XGMAC 3.01a DMA

This patch exports several DMA operations and descriptor tables from the
dwxgmac2 core to allow platform-specific code to override them. This
override allows the platform code to perform manual DMA address translations
required by the chip's internal AXI bus mappings.

> One consequence of the SoC-like design is that the internal AXI bus
> (used by the XGMAC for DMA) maps the PCI DMA space with a non-zero base
> address. This requires a translation step (happily just simple addition)
> to convert the PCI DMA address to the hardware DMA address.
> 
> This is pretty funky so rather than push that translation logic into
> the core driver we intend to keep that logic inside the TC956x
> platform code. In order to do that we need to export a few symbols
> to allow us to override some of the DMA and descriptor op tables.

This isn't a bug, but does this approach bypass the standard Linux DMA API?

The standard DMA API natively handles device-specific address offsets, such
as through dma_range_map on the struct device.

Could this address translation be handled using the standard DMA abstractions
instead of open-coding it via op-table overrides and exporting these internal
symbols?

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Sashiko AI review · https://sashiko.dev/#/patchset/20260501155421.3329862-1-elder@riscstar.com?part=7