Re: [PATCH] PCI: spacemit: Ignore PERST# bit for controllers

[Encrow Thorne]

On Wed Nov 4, 2026 at 10:07 PM CST, Ali Tariq wrote:

Hi Ali,
> The k1_pcie_init() does not set PCIE_IGNORE_PERSTN bit of the
> control logic register, which causes controller to reset itself once
> PERST# signal is asserted even when acting as host.
> On Orange Pi RV2 (SpacemiT K1), this resets the controller and wipes
> the IDs. k1_pcie_deinit() leaves PERST# asserted, so when k1_pcie_init()
> runs again, its first DBI access hangs the CPU.
>
> Set PCIE_IGNORE_PERSTN bit of the control logic register of APMU
> in k1_pcie_init() before enabling resources so controllers
> dont end up resetting themselves when PERST# signal is asserted.
>
> Fixes: ff64e078e45f ("PCI: spacemit: Add SpacemiT PCIe host driver")
> Signed-off-by: Ali Tariq <alitariq45892@xxxxxxxxx>
> ---
> Hang log: https://kernelci.cloud-v.co/scheduler/job/420
> Fixed Log: https://kernelci.cloud-v.co/scheduler/job/430
> ---
>  drivers/pci/controller/dwc/pcie-spacemit-k1.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
>
> diff --git a/drivers/pci/controller/dwc/pcie-spacemit-k1.c b/drivers/pci/controller/dwc/pcie-spacemit-k1.c
> index 92a71ea90ac3..af6028e8825a 100644
> --- a/drivers/pci/controller/dwc/pcie-spacemit-k1.c
> +++ b/drivers/pci/controller/dwc/pcie-spacemit-k1.c
> @@ -47,6 +47,7 @@
>  
>  #define PCIE_CONTROL_LOGIC			0x0004
>  #define PCIE_SOFT_RESET			BIT(0)
> +#define PCIE_IGNORE_PERSTN		BIT(2)	/* 1: ignore PERST# */
>  
>  struct k1_pcie {
>  	struct dw_pcie pci;
> @@ -131,11 +132,19 @@ static int k1_pcie_init(struct dw_pcie_rp *pp)
>  	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
>  	struct k1_pcie *k1 = to_k1_pcie(pci);
>  	u32 reset_ctrl;
> +	u32 ctrl_logic;
>  	u32 val;
>  	int ret;
>  
>  	k1_pcie_toggle_soft_reset(k1);
>  
> +	/*
> +	 * Ignore the PERST# signal so the controller does not reset
> +	 * itself when it pulls PERST# low.
> +	 */
> +	ctrl_logic = k1->pmu_off + PCIE_CONTROL_LOGIC;
> +	regmap_set_bits(k1->pmu, ctrl_logic, PCIE_IGNORE_PERSTN);
> +
>  	ret = k1_pcie_enable_resources(k1);
>  	if (ret)
>  		return ret;

Thanks for investigating this and submitting a fix.

Our testing also confirms that setting PCIE_IGNORE_PERSTN prevents
PERST# from resetting the local RC and resolves the DBI hang.

I will send a v2 of my earlier patch with an updated explanation
and the test results.

Regards,
Encrow Thorne