From: Nadeem Athani <nadeem@xxxxxxxxxxx> Cadence controller will not initiate autonomous speed change if strapped as Gen2. The Retrain Link bit is set as quirk to enable this speed change. Signed-off-by: Nadeem Athani <nadeem@xxxxxxxxxxx> [kishon@xxxxxx: Enable the workaround for TI's J721E SoC] Signed-off-by: Kishon Vijay Abraham I <kishon@xxxxxx> --- Hi Lorenzo, The previous version of the patch can be found at [1]. I slightly re-worked the patch from Nadeem *) Removed additional Link Up Check *) Removed quirk from pcie-cadence-plat.c *) Also removed additional compatible "cdns,cdns-pcie-host-quirk-retrain" added in that series *) Enabled the quirk for J721E [1] -> http://lore.kernel.org/r/20201211144236.3825-1-nadeem@xxxxxxxxxxx drivers/pci/controller/cadence/pci-j721e.c | 3 + .../controller/cadence/pcie-cadence-host.c | 67 ++++++++++++++----- drivers/pci/controller/cadence/pcie-cadence.h | 11 ++- 3 files changed, 62 insertions(+), 19 deletions(-) diff --git a/drivers/pci/controller/cadence/pci-j721e.c b/drivers/pci/controller/cadence/pci-j721e.c index dac1ac8a7615..baf729850cb1 100644 --- a/drivers/pci/controller/cadence/pci-j721e.c +++ b/drivers/pci/controller/cadence/pci-j721e.c @@ -64,6 +64,7 @@ enum j721e_pcie_mode { struct j721e_pcie_data { enum j721e_pcie_mode mode; + bool quirk_retrain_flag; }; static inline u32 j721e_pcie_user_readl(struct j721e_pcie *pcie, u32 offset) @@ -280,6 +281,7 @@ static struct pci_ops cdns_ti_pcie_host_ops = { static const struct j721e_pcie_data j721e_pcie_rc_data = { .mode = PCI_MODE_RC, + .quirk_retrain_flag = true, }; static const struct j721e_pcie_data j721e_pcie_ep_data = { @@ -388,6 +390,7 @@ static int j721e_pcie_probe(struct platform_device *pdev) bridge->ops = &cdns_ti_pcie_host_ops; rc = pci_host_bridge_priv(bridge); + rc->quirk_retrain_flag = data->quirk_retrain_flag; cdns_pcie = &rc->pcie; cdns_pcie->dev = dev; diff --git a/drivers/pci/controller/cadence/pcie-cadence-host.c b/drivers/pci/controller/cadence/pcie-cadence-host.c index 811c1cb2e8de..773c0d1137ed 100644 --- a/drivers/pci/controller/cadence/pcie-cadence-host.c +++ b/drivers/pci/controller/cadence/pcie-cadence-host.c @@ -77,6 +77,50 @@ static struct pci_ops cdns_pcie_host_ops = { .write = pci_generic_config_write, }; +static int cdns_pcie_host_wait_for_link(struct cdns_pcie *pcie) +{ + struct device *dev = pcie->dev; + int retries; + + /* Check if the link is up or not */ + for (retries = 0; retries < LINK_WAIT_MAX_RETRIES; retries++) { + if (cdns_pcie_link_up(pcie)) { + dev_info(dev, "Link up\n"); + return 0; + } + usleep_range(LINK_WAIT_USLEEP_MIN, LINK_WAIT_USLEEP_MAX); + } + + return -ETIMEDOUT; +} + +static void cdns_pcie_retrain(struct cdns_pcie *pcie) +{ + u32 lnk_cap_sls, pcie_cap_off = CDNS_PCIE_RP_CAP_OFFSET; + u16 lnk_stat, lnk_ctl; + + /* + * Set retrain bit if current speed is 2.5 GB/s, + * but the PCIe root port support is > 2.5 GB/s. + */ + + lnk_cap_sls = cdns_pcie_readl(pcie, (CDNS_PCIE_RP_BASE + pcie_cap_off + + PCI_EXP_LNKCAP)); + if ((lnk_cap_sls & PCI_EXP_LNKCAP_SLS) <= PCI_EXP_LNKCAP_SLS_2_5GB) + return; + + lnk_stat = cdns_pcie_rp_readw(pcie, pcie_cap_off + PCI_EXP_LNKSTA); + if ((lnk_stat & PCI_EXP_LNKSTA_CLS) == PCI_EXP_LNKSTA_CLS_2_5GB) { + lnk_ctl = cdns_pcie_rp_readw(pcie, + pcie_cap_off + PCI_EXP_LNKCTL); + lnk_ctl |= PCI_EXP_LNKCTL_RL; + cdns_pcie_rp_writew(pcie, pcie_cap_off + PCI_EXP_LNKCTL, + lnk_ctl); + + if (cdns_pcie_host_wait_for_link(pcie)) + return; + } +} static int cdns_pcie_host_init_root_port(struct cdns_pcie_rc *rc) { @@ -398,23 +442,6 @@ static int cdns_pcie_host_init(struct device *dev, return cdns_pcie_host_init_address_translation(rc); } -static int cdns_pcie_host_wait_for_link(struct cdns_pcie *pcie) -{ - struct device *dev = pcie->dev; - int retries; - - /* Check if the link is up or not */ - for (retries = 0; retries < LINK_WAIT_MAX_RETRIES; retries++) { - if (cdns_pcie_link_up(pcie)) { - dev_info(dev, "Link up\n"); - return 0; - } - usleep_range(LINK_WAIT_USLEEP_MIN, LINK_WAIT_USLEEP_MAX); - } - - return -ETIMEDOUT; -} - int cdns_pcie_host_setup(struct cdns_pcie_rc *rc) { struct device *dev = rc->pcie.dev; @@ -458,8 +485,12 @@ int cdns_pcie_host_setup(struct cdns_pcie_rc *rc) } ret = cdns_pcie_host_wait_for_link(pcie); - if (ret) + if (ret) { dev_dbg(dev, "PCIe link never came up\n"); + } else { + if (rc->quirk_retrain_flag) + cdns_pcie_retrain(pcie); + } for (bar = RP_BAR0; bar <= RP_NO_BAR; bar++) rc->avail_ib_bar[bar] = true; diff --git a/drivers/pci/controller/cadence/pcie-cadence.h b/drivers/pci/controller/cadence/pcie-cadence.h index 30eba6cafe2c..0f29128a5d0a 100644 --- a/drivers/pci/controller/cadence/pcie-cadence.h +++ b/drivers/pci/controller/cadence/pcie-cadence.h @@ -119,7 +119,7 @@ * Root Port Registers (PCI configuration space for the root port function) */ #define CDNS_PCIE_RP_BASE 0x00200000 - +#define CDNS_PCIE_RP_CAP_OFFSET 0xc0 /* * Address Translation Registers @@ -291,6 +291,7 @@ struct cdns_pcie { * @device_id: PCI device ID * @avail_ib_bar: Satus of RP_BAR0, RP_BAR1 and RP_NO_BAR if it's free or * available + * @quirk_retrain_flag: Retrain link as quirk for PCIe Gen2 */ struct cdns_pcie_rc { struct cdns_pcie pcie; @@ -299,6 +300,7 @@ struct cdns_pcie_rc { u32 vendor_id; u32 device_id; bool avail_ib_bar[CDNS_PCIE_RP_MAX_IB]; + bool quirk_retrain_flag; }; /** @@ -414,6 +416,13 @@ static inline void cdns_pcie_rp_writew(struct cdns_pcie *pcie, cdns_pcie_write_sz(addr, 0x2, value); } +static inline u16 cdns_pcie_rp_readw(struct cdns_pcie *pcie, u32 reg) +{ + void __iomem *addr = pcie->reg_base + CDNS_PCIE_RP_BASE + reg; + + return cdns_pcie_read_sz(addr, 0x2); +} + /* Endpoint Function register access */ static inline void cdns_pcie_ep_fn_writeb(struct cdns_pcie *pcie, u8 fn, u32 reg, u8 value) -- 2.17.1
