Re: [PATCH 2/2] PCI: of: Avoid config reads for disabled bridge nodes

[sashiko-bot@kernel.org]

> 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 of one of these powered-off port functions during
> PCI enumeration raises an Arm SError and prevents the board from booting.
> 
> A Configuration Read request to an unavailable port receives no
> completion and results in a Completion Timeout. The PCIe Root Complex
> reports that timeout as an AXI bus error, which triggers an SError on the
> CPU. The link between the Root Port and the switch upstream port remains
> up, so blocking config accesses only when the Root Port link is down
> does not prevent these accesses.
> 
> Commit 1a8c251cff20 ("PCI: move OF status = "disabled" detection to
> dev->match_driver") kept disabled PCI functions discoverable so that PCI
> fixups could still run, while suppressing driver binding later. Preserve
> [ ... ]
> Link: https://lore.kernel.org/all/fsrr5xg4plfknfcvv5co4ciklz5pywa5bbfxbthwsnjevysr5v@myghuxblnend/
> Link: https://lore.kernel.org/all/r22to3joold7ugzwolni4qahyumcekbyugrl2bms3xmiysqtgo@hu5s3dnyqwsj/
> Acked-by: Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>
> Tested-by: Daniele Briguglio <hello@superkali.me>
> Signed-off-by: Xilin Wu <sophon@radxa.com>

Sashiko has reviewed this patch and found no issues. It looks great!

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Sashiko AI review · https://sashiko.dev/#/patchset/20261009-pci-of-disabled-bridges-v1-0-08708f9e1802@radxa.com?part=2