Re: [PATCH] PCI: spacemit: Ignore link partner PERST on K1

[Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>]

On 2026-09-24 10:04 +0800, Encrow Thorne wrote:
> The K1 PCIe controller and PHY are affected by the PERST signal from
> the link partner during initialization. With some devices connected,
> this can prevent host initialization from progressing and cause the
> system to hang while probing the PCIe controller.
> 
> Set PCIE_IGNORE_PERSTN before accessing the DBI registers. When set,
> this bit makes both the PCIe controller and PHY ignore the PERST
> signal from the link partner.
> 
> This allows host initialization to complete without being affected by
> the link partner's PERST state.
> 
> Signed-off-by: Encrow Thorne <encrow.thorne@linux.spacemit.com>
> ---
>  drivers/pci/controller/dwc/pcie-spacemit-k1.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/drivers/pci/controller/dwc/pcie-spacemit-k1.c b/drivers/pci/controller/dwc/pcie-spacemit-k1.c
> index 0564c46e2f48..98f067e1ba81 100644
> --- a/drivers/pci/controller/dwc/pcie-spacemit-k1.c
> +++ b/drivers/pci/controller/dwc/pcie-spacemit-k1.c
> @@ -44,6 +44,7 @@
>  
>  #define PCIE_CONTROL_LOGIC			0x0004
>  #define PCIE_SOFT_RESET			BIT(0)
> +#define PCIE_IGNORE_PERSTN			BIT(2)
>  
>  struct k1_pcie {
>  	struct dw_pcie pci;
> @@ -137,6 +138,13 @@ static int k1_pcie_init(struct dw_pcie_rp *pp)
>  	if (ret)
>  		return ret;
>  
> +	/*
> +	 * When set to 1, the PCIe controller and PHY ignore the PERST signal
> +	 * from the link partner in both RC and EP modes.
> +	 */

What? PERST# is an output signal to RC and input to Endpoint. PERST# is not
controlled by the Endpoint, but only by the RC/host.

- Mani