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Message-ID: <20210209144622.26683-3-nadeem@cadence.com>
Date: Tue, 9 Feb 2021 15:46:22 +0100
From: Nadeem Athani <nadeem@...ence.com>
To: <tjoseph@...ence.com>, <lorenzo.pieralisi@....com>,
<robh@...nel.org>, <bhelgaas@...gle.com>,
<linux-pci@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
<kishon@...com>
CC: <nadeem@...ence.com>, <mparab@...ence.com>, <sjakhade@...ence.com>,
<pthombar@...ence.com>
Subject: [PATCH v8 2/2] PCI: cadence: Retrain Link to work around Gen2 training defect.
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@...ence.com>
---
drivers/pci/controller/cadence/pci-j721e.c | 3 ++
drivers/pci/controller/cadence/pcie-cadence-host.c | 48 +++++++++++++++++++++-
drivers/pci/controller/cadence/pcie-cadence.h | 11 ++++-
3 files changed, 60 insertions(+), 2 deletions(-)
diff --git a/drivers/pci/controller/cadence/pci-j721e.c b/drivers/pci/controller/cadence/pci-j721e.c
index dac1ac8a7615..849f1e416ea5 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 9f7aa718c8d4..6f591d382578 100644
--- a/drivers/pci/controller/cadence/pcie-cadence-host.c
+++ b/drivers/pci/controller/cadence/pcie-cadence-host.c
@@ -94,6 +94,52 @@ static int cdns_pcie_host_wait_for_link(struct cdns_pcie *pcie)
return -ETIMEDOUT;
}
+static int cdns_pcie_retrain(struct cdns_pcie *pcie)
+{
+ u32 lnk_cap_sls, pcie_cap_off = CDNS_PCIE_RP_CAP_OFFSET;
+ u16 lnk_stat, lnk_ctl;
+ int ret = 0;
+
+ /*
+ * 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 ret;
+
+ 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);
+
+ ret = cdns_pcie_host_wait_for_link(pcie);
+ }
+ return ret;
+}
+
+static int cdns_pcie_host_start_link(struct cdns_pcie_rc *rc)
+{
+ struct cdns_pcie *pcie = &rc->pcie;
+ int ret;
+
+ ret = cdns_pcie_host_wait_for_link(pcie);
+
+ /*
+ * Retrain link for Gen2 training defect
+ * if quirk flag is set.
+ */
+ if (!ret && rc->quirk_retrain_flag)
+ ret = cdns_pcie_retrain(pcie);
+
+ return ret;
+}
+
static int cdns_pcie_host_init_root_port(struct cdns_pcie_rc *rc)
{
struct cdns_pcie *pcie = &rc->pcie;
@@ -456,7 +502,7 @@ int cdns_pcie_host_setup(struct cdns_pcie_rc *rc)
return ret;
}
- ret = cdns_pcie_host_wait_for_link(pcie);
+ ret = cdns_pcie_host_start_link(rc);
if (ret)
dev_dbg(dev, "PCIe link never came up\n");
diff --git a/drivers/pci/controller/cadence/pcie-cadence.h b/drivers/pci/controller/cadence/pcie-cadence.h
index 30eba6cafe2c..254d2570f8c9 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)
--
2.15.0
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