Hi all. I found the fix to this problem a while back, when looking into getting magic packet detection working for wake-on-lan (I think I discovered that this would never work. I had a bunch of documentation about it but can't find it right now).
Anyway, the scattered ping timings (this is on the ethernet controller eth0, the usb ethernet adapter eth1 doesn't have this problem) are due to an interrupt not being serviced when the CPU is in sleep states. I think the gist of it is that it's a hardware bug in the CPU, where the interrupt gets masked and doesn't wake up the cpu, and so it only gets serviced when something else wakes it up (this would explain why the ping timings are seemingly random). There's a workaround where you can route the interrupt through a different pin, you just need to apply the changes in the kernel and compile/install. Here's what I got from rummaging around freescale mailing lists (I can try to dig up the threads if anyone is interested).
You need to add this to the FEC device tree entry in imx6q-novena.dts:
compatible = "fsl,imx6q-fec";
reg = <0x02188000 0x4000>;
interrupts-extended = <&gpio1 6 IRQ_TYPE_LEVEL_HIGH>,
<&intc 0 119 IRQ_TYPE_LEVEL_HIGH>;
fsl,magic-packet;
fsl,err006687-workaround-present;
So the entry now looks like:
&fec {
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_enet_novena>;
phy-mode = "rgmii";
phy-reset-gpios = <&gpio3 23 GPIO_ACTIVE_HIGH>;
rxc-skew-ps = <3000>;
rxdv-skew-ps = <0>;
txc-skew-ps = <3000>;
txen-skew-ps = <0>;
rxd0-skew-ps = <0>;
rxd1-skew-ps = <0>;
rxd2-skew-ps = <0>;
rxd3-skew-ps = <0>;
txd0-skew-ps = <3000>;
txd1-skew-ps = <3000>;
txd2-skew-ps = <3000>;
txd3-skew-ps = <3000>;
status = "okay";
compatible = "fsl,imx6q-fec";
reg = <0x02188000 0x4000>;
interrupts-extended = <&gpio1 6 IRQ_TYPE_LEVEL_HIGH>,
<&intc 0 119 IRQ_TYPE_LEVEL_HIGH>;
fsl,magic-packet;
fsl,err006687-workaround-present;
};
And add this to pinctrl_enet_novena:
MX6QDL_PAD_GPIO_6__ENET_IRQ 0x000b1
so it looks like this:
enet {
pinctrl_enet_novena: enetgrp-novena {
fsl,pins = <
MX6QDL_PAD_ENET_MDIO__ENET_MDIO 0x1b0b0
MX6QDL_PAD_ENET_MDC__ENET_MDC 0x1b0b0
MX6QDL_PAD_RGMII_TXC__RGMII_TXC 0x1b020
MX6QDL_PAD_RGMII_TD0__RGMII_TD0 0x1b028
MX6QDL_PAD_RGMII_TD1__RGMII_TD1 0x1b028
MX6QDL_PAD_RGMII_TD2__RGMII_TD2 0x1b028
MX6QDL_PAD_RGMII_TD3__RGMII_TD3 0x1b028
MX6QDL_PAD_RGMII_TX_CTL__RGMII_TX_CTL 0x1b028
MX6QDL_PAD_ENET_REF_CLK__ENET_TX_CLK 0x1b0b0
MX6QDL_PAD_RGMII_RXC__RGMII_RXC 0x1b0b0
MX6QDL_PAD_RGMII_RD0__RGMII_RD0 0x1b0b0
MX6QDL_PAD_RGMII_RD1__RGMII_RD1 0x1b0b0
MX6QDL_PAD_RGMII_RD2__RGMII_RD2 0x1b0b0
MX6QDL_PAD_RGMII_RD3__RGMII_RD3 0x1b0b0
MX6QDL_PAD_RGMII_RX_CTL__RGMII_RX_CTL 0x1b0b0
MX6QDL_PAD_GPIO_16__ENET_REF_CLK 0x4001b0a8
/* Ethernet reset */
MX6QDL_PAD_EIM_D23__GPIO3_IO23 0x80000000
/* IRQ workaround */
MX6QDL_PAD_GPIO_6__ENET_IRQ 0x000b1
>;
};
};
I also applied this patch I found:
From 29380905565655bb797bf670a173bddb8e641da6 Mon Sep 17 00:00:00 2001
From: Lucas Stach <l.stach@pengutronix.de>
Date: Fri, 3 Jun 2016 18:31:19 +0200
Subject: [PATCH] ARM: imx6: disable deeper idle states when FEC is active w/o
HW workaround
The i.MX6 Q/DL has an erratum (ERR006687) that prevents the FEC from
waking the CPUs when they are in wait(unclocked) state. As the hardware
workaround isn't applicable to all boards, disable the deeper idle state
when the workaround isn't present and the FEC is in use.
This allows to safely run a kernel with CPUidle enabled on all i.MX6
boards.
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Acked-by: David S. Miller <davem@davemloft.net> (for network changes)
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
---
Documentation/devicetree/bindings/net/fsl-fec.txt | 3 +++
arch/arm/mach-imx/cpuidle-imx6q.c | 16 +++++++++++++++
drivers/net/ethernet/freescale/fec.h | 2 ++
drivers/net/ethernet/freescale/fec_main.c | 12 +++++++++++
include/soc/imx/cpuidle.h | 25 +++++++++++++++++++++++
5 files changed, 58 insertions(+)
create mode 100644 include/soc/imx/cpuidle.h
diff --git a/Documentation/devicetree/bindings/net/fsl-fec.txt b/Documentation/devicetree/bindings/net/fsl-fec.txt
index b037a9d78d93..a1e3693cca16 100644
--- a/Documentation/devicetree/bindings/net/fsl-fec.txt
+++ b/Documentation/devicetree/bindings/net/fsl-fec.txt
@@ -27,6 +27,9 @@ Optional properties:
number to 1.
- fsl,magic-packet : If present, indicates that the hardware supports waking
up via magic packet.
+- fsl,err006687-workaround-present: If present indicates that the system has
+ the hardware workaround for ERR006687 applied and does not need a software
+ workaround.
Optional subnodes:
- mdio : specifies the mdio bus in the FEC, used as a container for phy nodes
diff --git a/arch/arm/mach-imx/cpuidle-imx6q.c b/arch/arm/mach-imx/cpuidle-imx6q.c
index 353bb8774112..c3cc8ca8d2ff 100644
--- a/arch/arm/mach-imx/cpuidle-imx6q.c
+++ b/arch/arm/mach-imx/cpuidle-imx6q.c
@@ -62,6 +62,22 @@ static struct cpuidle_driver imx6q_cpuidle_driver = {
.safe_state_index = 0,
};
+/*
+ * i.MX6 Q/DL has an erratum (ERR006687) that prevents the FEC from waking the
+ * CPUs when they are in wait(unclocked) state. As the hardware workaround isn't
+ * applicable to all boards, disable the deeper idle state when the workaround
+ * isn't present and the FEC is in use.
+ */
+void imx6q_cpuidle_fec_irqs_used(void)
+{
+ imx6q_cpuidle_driver.states[1].disabled = true;
+}
+
+void imx6q_cpuidle_fec_irqs_unused(void)
+{
+ imx6q_cpuidle_driver.states[1].disabled = false;
+}
+
int __init imx6q_cpuidle_init(void)
{
/* Set INT_MEM_CLK_LPM bit to get a reliable WAIT mode support */
diff --git a/drivers/net/ethernet/freescale/fec.h b/drivers/net/ethernet/freescale/fec.h
index f58f9ea51639..dc71a88e9c55 100644
--- a/drivers/net/ethernet/freescale/fec.h
+++ b/drivers/net/ethernet/freescale/fec.h
@@ -442,6 +442,8 @@ struct bufdesc_ex {
#define FEC_QUIRK_SINGLE_MDIO (1 << 11)
/* Controller supports RACC register */
#define FEC_QUIRK_HAS_RACC (1 << 12)
+/* Interrupt doesn't wake CPU from deep idle */
+#define FEC_QUIRK_ERR006687 (1 << 13)
struct bufdesc_prop {
int qid;
diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c
index ca2cccc594fd..8c2110b61684 100644
--- a/drivers/net/ethernet/freescale/fec_main.c
+++ b/drivers/net/ethernet/freescale/fec_main.c
@@ -60,6 +60,7 @@
#include <linux/if_vlan.h>
#include <linux/pinctrl/consumer.h>
#include <linux/prefetch.h>
+#include <soc/imx/cpuidle.h>
#include <asm/cacheflush.h>
@@ -2820,6 +2821,9 @@ fec_enet_open(struct net_device *ndev)
if (ret)
goto err_enet_mii_probe;
+ if (fep->quirks & FEC_QUIRK_ERR006687)
+ imx6q_cpuidle_fec_irqs_used();
+
napi_enable(&fep->napi);
phy_start(ndev->phydev);
netif_tx_start_all_queues(ndev);
@@ -2855,6 +2859,9 @@ fec_enet_close(struct net_device *ndev)
phy_disconnect(ndev->phydev);
+ if (fep->quirks & FEC_QUIRK_ERR006687)
+ imx6q_cpuidle_fec_irqs_unused();
+
fec_enet_clk_enable(ndev, false);
pinctrl_pm_select_sleep_state(&fep->pdev->dev);
pm_runtime_mark_last_busy(&fep->pdev->dev);
@@ -3294,6 +3301,11 @@ fec_probe(struct platform_device *pdev)
platform_set_drvdata(pdev, ndev);
+ if ((of_machine_is_compatible("fsl,imx6q") ||
+ of_machine_is_compatible("fsl,imx6dl")) &&
+ !of_property_read_bool(np, "fsl,err006687-workaround-present"))
+ fep->quirks |= FEC_QUIRK_ERR006687;
+
if (of_get_property(np, "fsl,magic-packet", NULL))
fep->wol_flag |= FEC_WOL_HAS_MAGIC_PACKET;
diff --git a/include/soc/imx/cpuidle.h b/include/soc/imx/cpuidle.h
new file mode 100644
index 000000000000..986a4823bce1
--- /dev/null
+++ b/include/soc/imx/cpuidle.h
@@ -0,0 +1,25 @@
+/*
+ * Copyright 2016 Pengutronix, <kernel@pengutronix.de>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ */
+
+#ifndef __SOC_IMX_CPUIDLE_H__
+#define __SOC_IMX_CPUIDLE_H__
+
+#if defined(CONFIG_CPU_IDLE) && defined(CONFIG_SOC_IMX6Q)
+void imx6q_cpuidle_fec_irqs_used(void);
+void imx6q_cpuidle_fec_irqs_unused(void);
+#else
+void imx6q_cpuidle_fec_irqs_used(void) { }
+void imx6q_cpuidle_fec_irqs_unused(void) { }
+#endif
+
+#endif /* __SOC_IMX_CPUIDLE_H__ */
--
2.11.0