[PATCH 06/12] PCI: tegra: Enable opportunistic update FC and ACK

Manikanta Maddireddy
2017-10-27T19:29:23Z

This patch ensures that DL sends pending ACKs and update FC packets when
link is idle instead of waiting for timers to expire which improves PCIe
bandwidth.

Signed-off-by: Manikanta Maddireddy <mmaddireddy@nvidia.com>
---
drivers/pci/host/pci-tegra.c | 15 ++++++++++++++-
1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/host/pci-tegra.c b/drivers/pci/host/pci-tegra.c
index af34daf3c6a2..27a8211c48b2 100644
--- a/drivers/pci/host/pci-tegra.c
+++ b/drivers/pci/host/pci-tegra.c
@@ -209,7 +209,9 @@
#define RP_ECTL_6_R2_RX_EQ_CTRL_H_1C_MASK 0xffffffff

#define RP_VEND_XP 0x00000f00
-#define RP_VEND_XP_DL_UP (1 << 30)
+#define RP_VEND_XP_DL_UP (1 << 30)
+#define RP_VEND_XP_OPPORTUNISTIC_ACK (1 << 27)
+#define RP_VEND_XP_OPPORTUNISTIC_UPDATEFC (1 << 28)

#define RP_VEND_CTL1 0xf48
#define RP_VEND_CTL1_ERPT (1 << 13)
@@ -2147,6 +2149,16 @@ static void tegra_pcie_enable_rp_features(struct tegra_pcie_port *port)
writel(value, port->base + RP_VEND_CTL1);
}

+static void tegra_pcie_apply_sw_fixup(struct tegra_pcie_port *port)
+{
+ unsigned long value;
+
+ /* Optimal settings to enhance bandwidth */
+ value = readl(port->base + RP_VEND_XP);
+ value |= RP_VEND_XP_OPPORTUNISTIC_ACK;
+ value |= RP_VEND_XP_OPPORTUNISTIC_UPDATEFC;
+ writel(value, port->base + RP_VEND_XP);
+}
/*
* FIXME: If there are no PCIe cards attached, then calling this function
* can result in the increase of the bootup time as there are big timeout
@@ -2215,6 +2227,7 @@ static void tegra_pcie_enable_ports(struct tegra_pcie *pcie)
if (soc->program_ectl_settings)
tegra_pcie_program_ectl_settings(port);
tegra_pcie_enable_rp_features(port);
+ tegra_pcie_apply_sw_fixup(port);
}

/* take the PCIe interface module out of reset */
--
2.1.4