Re: [PATCH v2] PCI: loongson: Override PCIe bridge supported speeds for older Loongson 3C6000 series steppings

Mingcong Bai
2026-01-04T11:03:30Z

Hi Ziyao Li,

在 2026/1/4 18:00, Ziyao Li via B4 Relay 写道:
> From: Ziyao Li <liziyao@uniontech.com>
>
> Older steppings of the Loongson 3C6000 series incorrectly report the
> supported link speeds on their PCIe bridges (device IDs 3c19, 3c29) as
> only 2.5 GT/s, despite the upstream bus supporting speeds from 2.5 GT/s
> up to 16 GT/s.
>
> As a result, certain PCIe devices would be incorrectly probed as a Gen1-
> only, even if higher link speeds are supported, harming performance and
> prevents dynamic link speed functionality from being enabled in drivers
> such as amdgpu.
>
> Manually override the `supported_speeds` field for affected PCIe bridges
> with those found on the upstream bus to correctly reflect the supported
> link speeds.
>
> This patch was originally found from AOSC OS[1].

Thanks for the patch. Looping loongarch.

Best Regards,
Mingcong Bai