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SubjectRe: [PATCH] PCI: Cadence: Add quirk for Gen2 controller to do autonomous speed change.
On Fri, Sep 18, 2020 at 4:34 AM Nadeem Athani <nadeem@cadence.com> wrote:
>
> Cadence controller will not initiate autonomous speed change if
> strapped as Gen2. The Retrain bit is set as a quirk to trigger
> this speed change.
>
> Signed-off-by: Nadeem Athani <nadeem@cadence.com>
> ---
> drivers/pci/controller/cadence/pcie-cadence-host.c | 13 +++++++++++++
> drivers/pci/controller/cadence/pcie-cadence.h | 6 ++++++
> 2 files changed, 19 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/pci/controller/cadence/pcie-cadence-host.c b/drivers/pci/controller/cadence/pcie-cadence-host.c
> index 4550e0d..4cb7f29 100644
> --- a/drivers/pci/controller/cadence/pcie-cadence-host.c
> +++ b/drivers/pci/controller/cadence/pcie-cadence-host.c
> @@ -83,6 +83,8 @@ static int cdns_pcie_host_init_root_port(struct cdns_pcie_rc *rc)
> struct cdns_pcie *pcie = &rc->pcie;
> u32 value, ctrl;
> u32 id;
> + u32 link_cap = CDNS_PCIE_LINK_CAP_OFFSET;
> + u8 sls, lnk_ctl;
>
> /*
> * Set the root complex BAR configuration register:
> @@ -111,6 +113,17 @@ static int cdns_pcie_host_init_root_port(struct cdns_pcie_rc *rc)
> if (rc->device_id != 0xffff)
> cdns_pcie_rp_writew(pcie, PCI_DEVICE_ID, rc->device_id);
>
> + /* Quirk to enable autonomous speed change for GEN2 controller */
> + /* Reading Supported Link Speed value */
> + sls = PCI_EXP_LNKCAP_SLS &
> + cdns_pcie_rp_readb(pcie, link_cap + PCI_EXP_LNKCAP);
> + if (sls == PCI_EXP_LNKCAP_SLS_5_0GB) {
> + /* Since this a Gen2 controller, set Retrain Link(RL) bit */
> + lnk_ctl = cdns_pcie_rp_readb(pcie, link_cap + PCI_EXP_LNKCTL);
> + lnk_ctl |= PCI_EXP_LNKCTL_RL;
> + cdns_pcie_rp_writeb(pcie, link_cap + PCI_EXP_LNKCTL, lnk_ctl);

Why the byte accesses? This is a 16-bit register.

> + }
> +
> cdns_pcie_rp_writeb(pcie, PCI_CLASS_REVISION, 0);
> cdns_pcie_rp_writeb(pcie, PCI_CLASS_PROG, 0);
> cdns_pcie_rp_writew(pcie, PCI_CLASS_DEVICE, PCI_CLASS_BRIDGE_PCI);
> diff --git a/drivers/pci/controller/cadence/pcie-cadence.h b/drivers/pci/controller/cadence/pcie-cadence.h
> index feed1e3..075c263 100644
> --- a/drivers/pci/controller/cadence/pcie-cadence.h
> +++ b/drivers/pci/controller/cadence/pcie-cadence.h
> @@ -120,6 +120,7 @@
> */
> #define CDNS_PCIE_RP_BASE 0x00200000
>
> +#define CDNS_PCIE_LINK_CAP_OFFSET 0xC0
>
> /*
> * Address Translation Registers
> @@ -413,6 +414,11 @@ static inline void cdns_pcie_rp_writew(struct cdns_pcie *pcie,
> cdns_pcie_write_sz(addr, 0x2, value);
> }
>
> +static inline u8 cdns_pcie_rp_readb(struct cdns_pcie *pcie, u32 reg)
> +{
> + return readb(pcie->reg_base + CDNS_PCIE_RP_BASE + reg);
> +}
> +
> /* Endpoint Function register access */
> static inline void cdns_pcie_ep_fn_writeb(struct cdns_pcie *pcie, u8 fn,
> u32 reg, u8 value)
> --
> 1.7.1
>

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