[PATCH 11/12] PCI: tegra: Increase the deskew retry time

Manikanta Maddireddy
2017-10-27T19:29:28Z

Some times Gen2 to Gen1 link speed switching fails due to instability in
deskew logic on lane0 in Tegra210. Increase the deskew retry time to
resolve this issue.

Signed-off-by: Manikanta Maddireddy <mmaddireddy-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
---
drivers/pci/host/pci-tegra.c | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)

diff --git a/drivers/pci/host/pci-tegra.c b/drivers/pci/host/pci-tegra.c
index 9680bf7d0a95..db1ce74ba64a 100644
--- a/drivers/pci/host/pci-tegra.c
+++ b/drivers/pci/host/pci-tegra.c
@@ -222,6 +222,10 @@
#define RP_VEND_XP_OPPORTUNISTIC_UPDATEFC (1 << 28)
#define RP_VEND_XP_UPDATE_FC_THRESHOLD_MASK (0xff << 18)

+#define RP_VEND_CTL0 0xf44
+#define RP_VEND_CTL0_DSK_RST_PULSE_WIDTH_MASK (0xf << 12)
+#define RP_VEND_CTL0_DSK_RST_PULSE_WIDTH (0x9 << 12)
+
#define RP_VEND_CTL1 0xf48
#define RP_VEND_CTL1_ERPT (1 << 13)

@@ -316,6 +320,7 @@ struct tegra_pcie_soc {
bool program_ectl_settings;
bool update_clamp_threshold;
bool RAW_violation_fixup;
+ bool program_deskew_time;
};

static inline struct tegra_msi *to_tegra_msi(struct msi_controller *chip)
@@ -2214,6 +2219,16 @@ static void tegra_pcie_apply_sw_fixup(struct tegra_pcie_port *port)
value |= RP_VEND_XP_UPDATE_FC_THRESHOLD_MASK;
writel(value, port->base + RP_VEND_XP);
}
+
+ /* Tune deskew retry time to take care of Gen2 -> Gen1
+ * link speed change error in corner cases
+ */
+ if (soc->program_deskew_time) {
+ value = readl(port->base + RP_VEND_CTL0);
+ value &= ~RP_VEND_CTL0_DSK_RST_PULSE_WIDTH_MASK;
+ value |= RP_VEND_CTL0_DSK_RST_PULSE_WIDTH;
+ writel(value, port->base + RP_VEND_CTL0);
+ }
}
/*
* FIXME: If there are no PCIe cards attached, then calling this function
@@ -2352,6 +2367,7 @@ static const struct tegra_pcie_soc tegra20_pcie = {
.program_ectl_settings = false,
.update_clamp_threshold = false,
.RAW_violation_fixup = false,
+ .program_deskew_time = false,
};

static const struct tegra_pcie_soc tegra30_pcie = {
@@ -2371,6 +2387,7 @@ static const struct tegra_pcie_soc tegra30_pcie = {
.program_ectl_settings = false,
.update_clamp_threshold = false,
.RAW_violation_fixup = false,
+ .program_deskew_time = false,
};

static const struct tegra_pcie_soc tegra124_pcie = {
@@ -2389,6 +2406,7 @@ static const struct tegra_pcie_soc tegra124_pcie = {
.program_ectl_settings = false,
.update_clamp_threshold = true,
.RAW_violation_fixup = true,
+ .program_deskew_time = false,
};

static const struct tegra_pcie_soc tegra210_pcie = {
@@ -2415,6 +2433,7 @@ static const struct tegra_pcie_soc tegra210_pcie = {
.program_ectl_settings = true,
.update_clamp_threshold = true,
.RAW_violation_fixup = false,
+ .program_deskew_time = true,
};

static const struct tegra_pcie_soc tegra186_pcie = {
@@ -2434,6 +2453,7 @@ static const struct tegra_pcie_soc tegra186_pcie = {
.program_ectl_settings = false,
.update_clamp_threshold = false,
.RAW_violation_fixup = false,
+ .program_deskew_time = false,
};

static const struct of_device_id tegra_pcie_of_match[] = {
--
2.1.4