Re: [PATCH 1/4] PCI: dwc: Advertise L1 PM Substates only if driver requests it

[Niklas Cassel <cassel@kernel.org>]

On Tue, Nov 11, 2025 at 04:16:08PM -0600, Bjorn Helgaas wrote:
> --- a/drivers/pci/controller/dwc/pcie-designware-host.c
> +++ b/drivers/pci/controller/dwc/pcie-designware-host.c
> @@ -1060,6 +1060,8 @@ int dw_pcie_setup_rc(struct dw_pcie_rp *pp)
>  		PCI_COMMAND_MASTER | PCI_COMMAND_SERR;
>  	dw_pcie_writel_dbi(pci, PCI_COMMAND, val);
>  
> +	dw_pcie_config_l1ss(pci);

The name dw_pcie_config_l1ss() sounds like we are enabling l1ss.

I know naming is hard.

Perhaps dw_pcie_disable_unsupported_l1ss() ?

Or something similar.


> --- a/drivers/pci/controller/dwc/pcie-qcom.c
> +++ b/drivers/pci/controller/dwc/pcie-qcom.c
> @@ -1067,6 +1067,8 @@ static int qcom_pcie_init_2_7_0(struct qcom_pcie *pcie)
>  	val &= ~REQ_NOT_ENTR_L1;
>  	writel(val, pcie->parf + PARF_PM_CTRL);
>  
> +	pci->l1ss_support = true;
> +
>  	val = readl(pcie->parf + PARF_AXI_MSTR_WR_ADDR_HALT_V2);
>  	val |= EN;
>  	writel(val, pcie->parf + PARF_AXI_MSTR_WR_ADDR_HALT_V2);

While it seems like ops_2_7_0 is the only type that explicitly does a
register write to enable L1ss, other versions might have the register
as enabled by default, so it would be nice if Mani could confirm exactly
which versions that should set l1ss_support = true.


Kind regards,
Niklas