Re: [PATCH 1/6] PCI: of: Avoid config reads for disabled bridge nodes

[Xilin Wu]

On 9/2/2026 4:43 PM, Konrad Dybcio wrote:
> On 9/1/26 10:47 AM, Xilin Wu wrote:
> > The TC9563 PCI power-control driver powers off external downstream ports
> > whose device tree nodes have status = "disabled".
> >
> > On the Radxa Dragon Q8B, reading the Vendor ID from one of these
> > powered-off port functions during PCI enumeration raises an Arm SError
> > instead of returning an all-ones PCI error response. This prevents the
> > board from completing boot.
>
> I agree with the premise of the patch, but I'd like to understand why
> that happens - do you have any details?

Unfortunately, I don't have further details. The downstream kernel also 
includes a similar workaround, so I suspect it's related to how the 
TC9563 chip is designed.

> Konrad


--
Best regards,
Xilin Wu <sophon@xxxxxxxxx>