Re: [RFC PATCH v2 1/4] PCI: pcie-rockchip: add Link Control and Status Register 2

Bjorn Helgaas
2025-06-11T21:51:25Z

On Tue, Jun 10, 2025 at 06:19:49PM -0300, Geraldo Nascimento wrote:
> Link Control and Status Register 2 is not present in current
> pcie-rockchip.h definitions. Add it in preparation for
> setting it before Gen2 retraining.
>
> While at it, also reference other registers from offset at
> Capabilities Register through standard PCI definitions. Only
> RC registers have been touched, although in principle there's
> no functional change.
>
> Signed-off-by: Geraldo Nascimento <geraldogabriel@gmail.com>
> ---
> drivers/pci/controller/pcie-rockchip.h | 10 ++++++----
> 1 file changed, 6 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/pci/controller/pcie-rockchip.h b/drivers/pci/controller/pcie-rockchip.h
> index 5864a20323f2..90d98aa8830e 100644
> --- a/drivers/pci/controller/pcie-rockchip.h
> +++ b/drivers/pci/controller/pcie-rockchip.h
> @@ -155,17 +155,19 @@
> #define PCIE_EP_CONFIG_DID_VID (PCIE_EP_CONFIG_BASE + 0x00)
> #define PCIE_EP_CONFIG_LCS (PCIE_EP_CONFIG_BASE + 0xd0)
> #define PCIE_RC_CONFIG_RID_CCR (PCIE_RC_CONFIG_BASE + 0x08)
> -#define PCIE_RC_CONFIG_DCR (PCIE_RC_CONFIG_BASE + 0xc4)
> +#define PCIE_RC_CONFIG_CR (PCIE_RC_CONFIG_BASE + 0xc0)
> +#define PCIE_RC_CONFIG_DCR (PCIE_RC_CONFIG_CR + PCI_EXP_DEVCAP)

I would really like to see PCI_EXP_DEVCAP referenced in the source
where we currently use PCIE_RC_CONFIG_DCR. That way, cscope/tags/grep
will find the actual uses of PCI_EXP_DEVCAP, not just this #define of
PCIE_RC_CONFIG_DCR.

Something like this:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/pci/controller/pci-mvebu.c?id=v6.15#n265

> #define PCIE_RC_CONFIG_DCR_CSPL_SHIFT 18
> #define PCIE_RC_CONFIG_DCR_CSPL_LIMIT 0xff
> #define PCIE_RC_CONFIG_DCR_CPLS_SHIFT 26

Also use PCI_EXP_DEVCAP_PWR_VAL and PCI_EXP_DEVCAP_PWR_SCL here if
possible. And FIELD_GET()/FIELD_PREP(), which avoid the need to
define _SHIFT values.

I would do a pure conversion patch of the existing #defines. Then I
suspect you wouldn't need a patch to add the Link 2 registers at all
because you could just use the #defines from pci_regs.h.

> -#define PCIE_RC_CONFIG_DCSR (PCIE_RC_CONFIG_BASE + 0xc8)
> +#define PCIE_RC_CONFIG_DCSR (PCIE_RC_CONFIG_CR + PCI_EXP_DEVCTL)
> #define PCIE_RC_CONFIG_DCSR_MPS_MASK GENMASK(7, 5)
> #define PCIE_RC_CONFIG_DCSR_MPS_256 (0x1 << 5)
> -#define PCIE_RC_CONFIG_LINK_CAP (PCIE_RC_CONFIG_BASE + 0xcc)
> +#define PCIE_RC_CONFIG_LINK_CAP (PCIE_RC_CONFIG_CR + PCI_EXP_LNKCAP)
> #define PCIE_RC_CONFIG_LINK_CAP_L0S BIT(10)
> -#define PCIE_RC_CONFIG_LCS (PCIE_RC_CONFIG_BASE + 0xd0)
> +#define PCIE_RC_CONFIG_LCS (PCIE_RC_CONFIG_CR + PCI_EXP_LNKCTL)
> #define PCIE_EP_CONFIG_LCS (PCIE_EP_CONFIG_BASE + 0xd0)
> +#define PCIE_RC_CONFIG_LCS_2 (PCIE_RC_CONFIG_CR + PCI_EXP_LNKCTL2)
> #define PCIE_RC_CONFIG_L1_SUBSTATE_CTRL2 (PCIE_RC_CONFIG_BASE + 0x90c)
> #define PCIE_RC_CONFIG_THP_CAP (PCIE_RC_CONFIG_BASE + 0x274)
> #define PCIE_RC_CONFIG_THP_CAP_NEXT_MASK GENMASK(31, 20)
> --
> 2.49.0
>