[PATCH v3 1/2] PCI: dw-rockchip: Configure L1sub support

[Manivannan Sadhasivam]

On Thu, Oct 23, 2025 at 10:51:22AM +0800, Shawn Lin wrote:
> L1 PM Substates for RC mode require support in the dw-rockchip driver
> including proper handling of the CLKREQ# sideband signal. It is mostly
> handled by hardware, but software still needs to set the clkreq fields
> in the PCIE_CLIENT_POWER_CON register to match the hardware implementation.
> 
> For more details, see section '18.6.6.4 L1 Substate' in the RK3658 TRM 1.1
> Part 2, or section '11.6.6.4 L1 Substate' in the RK3588 TRM 1.0 Part2.
> 
> Meanwhile, for the EP mode, we haven't prepared enough to actually support
> L1 PM Substates yet. So disable it now until proper support is added later.
> 
> Signed-off-by: Shawn Lin <shawn.lin at rock-chips.com>
> 
> ---
> 
> Changes in v3:
> - rephrease the changelog
> - use FIELD_PREP_WM16
> - rename to rockchip_pcie_configure_l1sub
> - disable L1ss for EP mode
> 
> Changes in v2:
> - drop of_pci_clkreq_presnt API
> - drop dependency of Niklas's patch
> 
>  drivers/pci/controller/dwc/pcie-dw-rockchip.c | 43 +++++++++++++++++++++++++++
>  1 file changed, 43 insertions(+)
> 
> diff --git a/drivers/pci/controller/dwc/pcie-dw-rockchip.c b/drivers/pci/controller/dwc/pcie-dw-rockchip.c
> index 3e2752c..25d2474 100644
> --- a/drivers/pci/controller/dwc/pcie-dw-rockchip.c
> +++ b/drivers/pci/controller/dwc/pcie-dw-rockchip.c
> @@ -62,6 +62,12 @@
>  /* Interrupt Mask Register Related to Miscellaneous Operation */
>  #define PCIE_CLIENT_INTR_MASK_MISC	0x24
>  
> +/* Power Management Control Register */
> +#define PCIE_CLIENT_POWER_CON		0x2c
> +#define  PCIE_CLKREQ_READY		FIELD_PREP_WM16(BIT(0), 1)
> +#define  PCIE_CLKREQ_NOT_READY		FIELD_PREP_WM16(BIT(0), 0)
> +#define  PCIE_CLKREQ_PULL_DOWN		FIELD_PREP_WM16(GENMASK(13, 12), 1)
> +
>  /* Hot Reset Control Register */
>  #define PCIE_CLIENT_HOT_RESET_CTRL	0x180
>  #define  PCIE_LTSSM_APP_DLY2_EN		BIT(1)
> @@ -85,6 +91,7 @@ struct rockchip_pcie {
>  	struct regulator *vpcie3v3;
>  	struct irq_domain *irq_domain;
>  	const struct rockchip_pcie_of_data *data;
> +	bool supports_clkreq;
>  };
>  
>  struct rockchip_pcie_of_data {
> @@ -200,6 +207,37 @@ static bool rockchip_pcie_link_up(struct dw_pcie *pci)
>  	return FIELD_GET(PCIE_LINKUP_MASK, val) == PCIE_LINKUP;
>  }
>  
> +/*
> + * See e.g. section '11.6.6.4 L1 Substate' in the RK3588 TRM V1.0 for the steps
> + * needed to support L1 substates. Currently, just enable L1 substates for RC
> + * mode if CLKREQ# is properly connected and supports-clkreq is present in DT.
> + * For EP mode, there are more things should be done to actually save power in
> + * L1 substates, so disable L1 substates until there is proper support.
> + */
> +static void rockchip_pcie_configure_l1sub(struct dw_pcie *pci)
> +{
> +	struct rockchip_pcie *rockchip = to_rockchip_pcie(pci);
> +	u32 cap, l1subcap;
> +
> +	/* Enable L1 substates if CLKREQ# is properly connected */
> +	if (rockchip->supports_clkreq && rockchip->data->mode == DW_PCIE_RC_TYPE ) {
> +		rockchip_pcie_writel_apb(rockchip, PCIE_CLKREQ_READY, PCIE_CLIENT_POWER_CON);
> +		return;
> +	}
> +
> +	/* Otherwise, pull down CLKREQ# and disable L1 PM substates */
> +	rockchip_pcie_writel_apb(rockchip, PCIE_CLKREQ_PULL_DOWN | PCIE_CLKREQ_NOT_READY,
> +				 PCIE_CLIENT_POWER_CON);
> +	cap = dw_pcie_find_ext_capability(pci, PCI_EXT_CAP_ID_L1SS);
> +	if (cap) {
> +		l1subcap = dw_pcie_readl_dbi(pci, cap + PCI_L1SS_CAP);
> +		l1subcap &= ~(PCI_L1SS_CAP_L1_PM_SS | PCI_L1SS_CAP_ASPM_L1_1 |
> +			      PCI_L1SS_CAP_ASPM_L1_2 | PCI_L1SS_CAP_PCIPM_L1_1 |
> +			      PCI_L1SS_CAP_PCIPM_L1_2);
> +		dw_pcie_writel_dbi(pci, cap + PCI_L1SS_CAP, l1subcap);
> +	}
> +}
> +
>  static void rockchip_pcie_enable_l0s(struct dw_pcie *pci)
>  {
>  	u32 cap, lnkcap;
> @@ -264,6 +302,7 @@ static int rockchip_pcie_host_init(struct dw_pcie_rp *pp)
>  	irq_set_chained_handler_and_data(irq, rockchip_pcie_intx_handler,
>  					 rockchip);
>  
> +	rockchip_pcie_configure_l1sub(pci);
>  	rockchip_pcie_enable_l0s(pci);
>  
>  	return 0;
> @@ -301,6 +340,7 @@ static void rockchip_pcie_ep_init(struct dw_pcie_ep *ep)
>  	struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
>  	enum pci_barno bar;
>  
> +	rockchip_pcie_configure_l1sub(pci);

Didn't you agree to drop the EP change?

- Mani

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