From: Nadeem Athani <nadeem@xxxxxxxxxxx> PCIe fails to link up if SERDES lanes not used by PCIe are assigned to another protocol. For example, link training fails if lanes 2 and 3 are assigned to another protocol while lanes 0 and 1 are used for PCIe to form a two lane link. This failure is due to an incorrect tie-off on an internal status signal indicating electrical idle. Status signals going from SERDES to PCIe Controller are tied-off when a lane is not assigned to PCIe. Signal indicating electrical idle is incorrectly tied-off to a state that indicates non-idle. As a result, PCIe sees unused lanes to be out of electrical idle and this causes LTSSM to exit Detect.Quiet state without waiting for 12ms timeout to occur. If a receiver is not detected on the first receiver detection attempt in Detect.Active state, LTSSM goes back to Detect.Quiet and again moves forward to Detect.Active state without waiting for 12ms as required by PCIe base specification. Since wait time in Detect.Quiet is skipped, multiple receiver detect operations are performed back-to-back without allowing time for capacitance on the transmit lines to discharge. This causes subsequent receiver detection to always fail even if a receiver gets connected eventually. Add a quirk flag "quirk_detect_quiet_flag" to program the minimum time the LTSSM should wait on entering Detect.Quiet state here. This has to be set for J7200 as it has an incorrect tie-off on unused lanes. Signed-off-by: Nadeem Athani <nadeem@xxxxxxxxxxx> Signed-off-by: Kishon Vijay Abraham I <kishon@xxxxxx> --- Changes from v2: 1) Removed terminating '.' in subject 2) Modified commit log Changes from v1: 1) Add function cdns_pcie_detect_quiet_min_delay_set in pcie-cadence.c and invoke it from host and endpoint driver file. v2: https://lore.kernel.org/r/20210528155626.21793-1-nadeem@xxxxxxxxxxx v1: https://lore.kernel.org/r/20210426051427.15945-1-nadeem@xxxxxxxxxxx .../pci/controller/cadence/pcie-cadence-ep.c | 4 ++++ .../pci/controller/cadence/pcie-cadence-host.c | 3 +++ drivers/pci/controller/cadence/pcie-cadence.c | 17 +++++++++++++++++ drivers/pci/controller/cadence/pcie-cadence.h | 15 +++++++++++++++ 4 files changed, 39 insertions(+) diff --git a/drivers/pci/controller/cadence/pcie-cadence-ep.c b/drivers/pci/controller/cadence/pcie-cadence-ep.c index 791915054ff4..e05c157afef0 100644 --- a/drivers/pci/controller/cadence/pcie-cadence-ep.c +++ b/drivers/pci/controller/cadence/pcie-cadence-ep.c @@ -804,6 +804,10 @@ int cdns_pcie_ep_setup(struct cdns_pcie_ep *ep) ep->irq_pci_addr = CDNS_PCIE_EP_IRQ_PCI_ADDR_NONE; /* Reserve region 0 for IRQs */ set_bit(0, &ep->ob_region_map); + + if (ep->quirk_detect_quiet_flag) + cdns_pcie_detect_quiet_min_delay_set(&ep->pcie); + spin_lock_init(&ep->lock); return 0; diff --git a/drivers/pci/controller/cadence/pcie-cadence-host.c b/drivers/pci/controller/cadence/pcie-cadence-host.c index ae1c55503513..fb96d37a135c 100644 --- a/drivers/pci/controller/cadence/pcie-cadence-host.c +++ b/drivers/pci/controller/cadence/pcie-cadence-host.c @@ -498,6 +498,9 @@ int cdns_pcie_host_setup(struct cdns_pcie_rc *rc) return PTR_ERR(rc->cfg_base); rc->cfg_res = res; + if (rc->quirk_detect_quiet_flag) + cdns_pcie_detect_quiet_min_delay_set(&rc->pcie); + ret = cdns_pcie_start_link(pcie); if (ret) { dev_err(dev, "Failed to start link\n"); diff --git a/drivers/pci/controller/cadence/pcie-cadence.c b/drivers/pci/controller/cadence/pcie-cadence.c index 3c3646502d05..65b6c8bed0d4 100644 --- a/drivers/pci/controller/cadence/pcie-cadence.c +++ b/drivers/pci/controller/cadence/pcie-cadence.c @@ -7,6 +7,23 @@ #include "pcie-cadence.h" +void cdns_pcie_detect_quiet_min_delay_set(struct cdns_pcie *pcie) +{ + u32 delay = 0x3; + u32 ltssm_control_cap; + + /* + * Set the LTSSM Detect Quiet state min. delay to 2ms. + */ + + ltssm_control_cap = cdns_pcie_readl(pcie, CDNS_PCIE_LTSSM_CONTROL_CAP); + ltssm_control_cap = ((ltssm_control_cap & + ~CDNS_PCIE_DETECT_QUIET_MIN_DELAY_MASK) | + CDNS_PCIE_DETECT_QUIET_MIN_DELAY(delay)); + + cdns_pcie_writel(pcie, CDNS_PCIE_LTSSM_CONTROL_CAP, ltssm_control_cap); +} + void cdns_pcie_set_outbound_region(struct cdns_pcie *pcie, u8 busnr, u8 fn, u32 r, bool is_io, u64 cpu_addr, u64 pci_addr, size_t size) diff --git a/drivers/pci/controller/cadence/pcie-cadence.h b/drivers/pci/controller/cadence/pcie-cadence.h index 22ff4c9defd8..07d461f839be 100644 --- a/drivers/pci/controller/cadence/pcie-cadence.h +++ b/drivers/pci/controller/cadence/pcie-cadence.h @@ -194,6 +194,14 @@ /* AXI link down register */ #define CDNS_PCIE_AT_LINKDOWN (CDNS_PCIE_AT_BASE + 0x0824) +/* LTSSM Capabilities register */ +#define CDNS_PCIE_LTSSM_CONTROL_CAP (CDNS_PCIE_LM_BASE + 0x0054) +#define CDNS_PCIE_DETECT_QUIET_MIN_DELAY_MASK GENMASK(2, 1) +#define CDNS_PCIE_DETECT_QUIET_MIN_DELAY_SHIFT 1 +#define CDNS_PCIE_DETECT_QUIET_MIN_DELAY(delay) \ + (((delay) << CDNS_PCIE_DETECT_QUIET_MIN_DELAY_SHIFT) & \ + CDNS_PCIE_DETECT_QUIET_MIN_DELAY_MASK) + enum cdns_pcie_rp_bar { RP_BAR_UNDEFINED = -1, RP_BAR0, @@ -297,6 +305,7 @@ struct cdns_pcie { * @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 + * @quirk_detect_quiet_flag: LTSSM Detect Quiet min delay set as quirk */ struct cdns_pcie_rc { struct cdns_pcie pcie; @@ -306,6 +315,7 @@ struct cdns_pcie_rc { u32 device_id; bool avail_ib_bar[CDNS_PCIE_RP_MAX_IB]; bool quirk_retrain_flag; + bool quirk_detect_quiet_flag; }; /** @@ -338,6 +348,7 @@ struct cdns_pcie_epf { * registers fields (RMW) accessible by both remote RC and EP to * minimize time between read and write * @epf: Structure to hold info about endpoint function + * @quirk_detect_quiet_flag: LTSSM Detect Quiet min delay set as quirk */ struct cdns_pcie_ep { struct cdns_pcie pcie; @@ -352,6 +363,7 @@ struct cdns_pcie_ep { /* protect writing to PCI_STATUS while raising legacy interrupts */ spinlock_t lock; struct cdns_pcie_epf *epf; + bool quirk_detect_quiet_flag; }; @@ -512,6 +524,9 @@ static inline int cdns_pcie_ep_setup(struct cdns_pcie_ep *ep) return 0; } #endif + +void cdns_pcie_detect_quiet_min_delay_set(struct cdns_pcie *pcie); + void cdns_pcie_set_outbound_region(struct cdns_pcie *pcie, u8 busnr, u8 fn, u32 r, bool is_io, u64 cpu_addr, u64 pci_addr, size_t size); -- 2.17.1
