linux-kernel - [PATCH v2] dwc: dra7xx: Print link state to console for debug

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Date:   Thu, 19 Oct 2017 18:13:29 +0530
From:   Faiz Abbas <faiz_abbas@...com>
To:     <kishon@...com>
CC:     <bhelgaas@...gle.com>, <linux-omap@...r.kernel.org>,
        <linux-pci@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <faiz_abbas@...com>
Subject: [PATCH v2] dwc: dra7xx: Print link state to console for debug

Enable support for printing the LTSSM link state for debugging PCI
when link is down.

Signed-off-by: Faiz Abbas <faiz_abbas@...com>
---
v2:
 1. Changed dev_err() to dev_dbg()
 2. Changed static char array to static const char * const
 3. format changes

 drivers/pci/dwc/pci-dra7xx.c | 48 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 48 insertions(+)

diff --git a/drivers/pci/dwc/pci-dra7xx.c b/drivers/pci/dwc/pci-dra7xx.c
index 34427a6..0e70e77 100644
--- a/drivers/pci/dwc/pci-dra7xx.c
+++ b/drivers/pci/dwc/pci-dra7xx.c
@@ -98,6 +98,45 @@ struct dra7xx_pcie_of_data {
 
 #define to_dra7xx_pcie(x)	dev_get_drvdata((x)->dev)
 
+static const char * const state[] = {
+	"DETECT_QUIET",
+	"DETECT_ACT",
+	"POLL_ACTIVE",
+	"POLL_COMPLIANCE",
+	"POLL_CONFIG",
+	"PRE_DETECT_QUIET",
+	"DETECT_WAIT",
+	"CFG_LINKWD_START",
+	"CFG_LINKWD_ACEPT",
+	"CFG_LANENUM_WAIT",
+	"CFG_LANENUM_ACEPT",
+	"CFG_COMPLETE",
+	"CFG_IDLE",
+	"RCVRY_LOCK",
+	"RCVRY_SPEED",
+	"RCVRY_RCVRCFG",
+	"RCVRY_IDLE",
+	"L0",
+	"L0S",
+	"L123_SEND_EIDLE",
+	"L1_IDLE",
+	"L2_IDLE",
+	"L2_WAKE",
+	"DISABLED_ENTRY",
+	"DISABLED_IDLE",
+	"DISABLED",
+	"LPBK_ENTRY",
+	"LPBK_ACTIVE",
+	"LPBK_EXIT",
+	"LPBK_EXIT_TIMEOUT",
+	"HOT_RESET_ENTRY",
+	"HOT_RESET",
+	"RCVRY_EQ0",
+	"RCVRY_EQ1",
+	"RCVRY_EQ2",
+	"RCVRY_EQ3"
+};
+
 static inline u32 dra7xx_pcie_readl(struct dra7xx_pcie *pcie, u32 offset)
 {
 	return readl(pcie->base + offset);
@@ -118,6 +157,15 @@ static int dra7xx_pcie_link_up(struct dw_pcie *pci)
 {
 	struct dra7xx_pcie *dra7xx = to_dra7xx_pcie(pci);
 	u32 reg = dra7xx_pcie_readl(dra7xx, PCIECTRL_DRA7XX_CONF_PHY_CS);
+	u32 cmd_reg;
+	u32 ltssm_state;
+
+	if (!(reg & LINK_UP)) {
+		cmd_reg = dra7xx_pcie_readl(dra7xx,
+					    PCIECTRL_DRA7XX_CONF_DEVICE_CMD);
+		ltssm_state = (cmd_reg & GENMASK(7, 2)) >> 2;
+		dev_dbg(pci->dev, "Link state:%s\n", state[ltssm_state]);
+	}
 
 	return !!(reg & LINK_UP);
 }
-- 
2.7.4