[WIP] LoongArch: Add ACPI compatibility for ISA I/O space reservation #19
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This patch adds essential compatibility support for ACPI-based systems running on older firmware. Many older computers with old firmware still rely on this mechanism and are unlikely to receive futher firmeware updates. This change ensures proper ISA I/O space reservation across for them. Signed-off-by: Yinan Qin <a.elysia@proton.me>
elysia-best
changed the title
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Eww. This probably calls for a better (even DMI-specific) quirk... |
| pr_warn("Failed to allocate fwnode for legacy ISA\n"); | ||
| return 0; | ||
| } | ||
| if (add_legacy_isa_io(fwnode, LOONGSON_LIO_BASE, ISA_IOSIZE)) { |
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I don't think this patch can be merged as-is.
Both 7A1000 and 7A2000 manuals state that 0x18000000-0x1800ffff (64K) is for "LPC I/O", but this patch reserves 0x18000000-0x18003fff (16K). The only reference I can find about this 16K range is the 2K1000 ISA controller which is obviously unrelated to any desktop platform. The macro name ("ISA_IOSIZE") also seems something for 2K1000 now.
We need some detailed analysis of the issue and maybe some research on the ACPI specification.
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Right, a fast search for ISA_IOSIZE shows that this marco was introduced in initial commits for LoongArch support at torvalds@7153c3c
It didn't explain why this marco should be 16K rather than 64K. Additionally, ISA_IOSIZE is also used in loongnix's patch for this issue. I agree that this issue needs more analysis :)
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This patch adds essential compatibility support for ACPI-based systems running on older firmware. Some older computers with Kunlun firmware still rely on this mechanism and are unlikely to receive futher firmeware updates. This change ensures proper ISA I/O space reservation across for them.