Re: [BUG] PCI: spacemit-k1: port C probe hard-hangs a CPU with one endpoint on Milk-V Jupiter

[Manivannan Sadhasivam]

On Mon, Sep 21, 2026 at 01:55:42PM +0800, Encrow Thorne wrote:

[...]

> Hi Bruno,
> 
> The issue was caused by a missing hardware configuration in the K1 PCIe
> initialization.
> 
> The PMU PCIE_CONTROL_LOGIC register contains an IGNORE_PERSTN bit (BIT(2)).
> The hardware manual describes it as follows:
> 
> “When set to 1, the PCIe controller and PHY ignore the PERSTN signal from
> the link partner in both RC and EP modes.”
> 
> This bit was not configured during RC initialization. As a result, the
> controller and PHY could still be affected by the PERSTN input during the
> early DBI accesses. With the Intel I225-V installed, the first DBI access
> could remain pending and hang the CPU.
> 

What does this 'PERSTN' bit controls? PERST# or something else? PERST# is
controlled only by the Root Complex btw. Also, why does this missing register
configuration only affecting Intel I225-V endpoint and not others?

- Mani

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