[PATCH 3/8] pci: pcie_dw_rockchip: Speed up link probe

22 Apr 2023

Use a similar pattern and delay values as the linux mainline driver to
speed up failing when nothing is connected.
Reduce fail speed from around 5+ seconds down to around one second on a
Radxa ROCK 3 Model A, where pcie2x1 is probed before pcie3x2 M2 slot.
Signed-off-by: Jonas Karlman jonas@kwiboo.se
---
 drivers/pci/pcie_dw_rockchip.c | 68 ++++++++++++++++++----------------
 1 file changed, 37 insertions(+), 31 deletions(-)

diff --git a/drivers/pci/pcie_dw_rockchip.c b/drivers/pci/pcie_dw_rockchip.c
index a5b900f95981..fd3da47272b3 100644
--- a/drivers/pci/pcie_dw_rockchip.c
+++ b/drivers/pci/pcie_dw_rockchip.c
@@ -61,9 +61,6 @@ struct rk_pcie {
 #define PCIE_CLIENT_DBG_TRANSITION_DATA	0xffff0000
 #define PCIE_CLIENT_DBF_EN		0xffff0003
-/* Parameters for the waiting for #perst signal */
-#define MACRO_US			1000
-
 static int rk_pcie_read(void __iomem *addr, int size, u32 *val)
 {
    if ((uintptr_t)addr & (size - 1)) {
@@ -242,43 +239,46 @@ static int rk_pcie_link_up(struct rk_pcie *priv, u32 cap_speed)
    /* DW pre link configurations */
    rk_pcie_configure(priv, cap_speed);
-	/* Rest the device */
-	if (dm_gpio_is_valid(&priv->rst_gpio)) {
-		dm_gpio_set_value(&priv->rst_gpio, 0);
-		/*
-		 * Minimal is 100ms from spec but we see
-		 * some wired devices need much more, such as 600ms.
-		 * Add a enough delay to cover all cases.
-		 */
-		udelay(MACRO_US * 1000);
-		dm_gpio_set_value(&priv->rst_gpio, 1);
-	}
-
    rk_pcie_disable_ltssm(priv);
    rk_pcie_link_status_clear(priv);
    rk_pcie_enable_debug(priv);
+	/* Reset the device */
+	if (dm_gpio_is_valid(&priv->rst_gpio))
+		dm_gpio_set_value(&priv->rst_gpio, 0);
+
    /* Enable LTSSM */
    rk_pcie_enable_ltssm(priv);
-	for (retries = 0; retries < 5; retries++) {
-		if (is_link_up(priv)) {
-			dev_info(priv->dw.dev, "PCIe Link up, LTSSM is 0x%x\n",
-				 rk_pcie_readl_apb(priv, PCIE_CLIENT_LTSSM_STATUS));
-			rk_pcie_debug_dump(priv);
-			return 0;
-		}
-
-		dev_info(priv->dw.dev, "PCIe Linking... LTSSM is 0x%x\n",
-			 rk_pcie_readl_apb(priv, PCIE_CLIENT_LTSSM_STATUS));
-		rk_pcie_debug_dump(priv);
-		udelay(MACRO_US * 1000);
+	/*
+	 * PCIe requires the refclk to be stable for 100ms prior to releasing
+	 * PERST. See table 2-4 in section 2.6.2 AC Specifications of the PCI
+	 * Express Card Electromechanical Specification, 1.1. However, we don't
+	 * know if the refclk is coming from RC's PHY or external OSC. If it's
+	 * from RC, so enabling LTSSM is the just right place to release #PERST.
+	 */
+	mdelay(100);
+	if (dm_gpio_is_valid(&priv->rst_gpio))
+		dm_gpio_set_value(&priv->rst_gpio, 1);
+
+	/* Check if the link is up or not */
+	for (retries = 0; retries < 10; retries++) {
+		if (is_link_up(priv))
+			break;
+
+		mdelay(100);
+	}
+
+	if (retries >= 10) {
+		dev_err(priv->dw.dev, "PCIe-%d Link Fail\n",
+			dev_seq(priv->dw.dev));
+		return -EIO;
    }
-	dev_err(priv->dw.dev, "PCIe-%d Link Fail\n", dev_seq(priv->dw.dev));
-	/* Link maybe in Gen switch recovery but we need to wait more 1s */
-	udelay(MACRO_US * 1000);
-	return -EIO;
+	dev_info(priv->dw.dev, "PCIe Link up, LTSSM is 0x%x\n",
+		 rk_pcie_readl_apb(priv, PCIE_CLIENT_LTSSM_STATUS));
+	rk_pcie_debug_dump(priv);
+	return 0;
 }
static int rockchip_pcie_init_port(struct udevice *dev)
@@ -287,6 +287,12 @@ static int rockchip_pcie_init_port(struct udevice *dev)
    u32 val;
    struct rk_pcie *priv = dev_get_priv(dev);
+	ret = reset_assert_bulk(&priv->rsts);
+	if (ret) {
+		dev_err(dev, "failed to assert resets (ret=%d)\n", ret);
+		return ret;
+	}
+
    /* Set power and maybe external ref clk input */
    ret = regulator_set_enable_if_allowed(priv->vpcie3v3, true);
    if (ret && ret != -ENOSYS) {
-- 
2.40.0


    