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Date:	Mon, 6 Jun 2016 02:00:09 +0000
From:	Fugang Duan <fugang.duan@....com>
To:	Lucas Stach <l.stach@...gutronix.de>,
	Shawn Guo <shawnguo@...nel.org>
CC:	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"patchwork-lst@...gutronix.de" <patchwork-lst@...gutronix.de>,
	"kernel@...gutronix.de" <kernel@...gutronix.de>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: RE: [PATCH v2 1/2] ARM: imx6: disable deeper idle states when FEC is
 active w/o HW workaround

From: Lucas Stach <l.stach@...gutronix.de> Sent: Saturday, June 04, 2016 12:31 AM
> To: Shawn Guo <shawnguo@...nel.org>; Fugang Duan <fugang.duan@....com>
> Cc: devicetree@...r.kernel.org; patchwork-lst@...gutronix.de;
> kernel@...gutronix.de; linux-arm-kernel@...ts.infradead.org;
> netdev@...r.kernel.org
> Subject: [PATCH v2 1/2] 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@...gutronix.de>
> Acked-by: David S. Miller <davem@...emloft.net> (for network changes)
> ---
> v2: Spell out "workaround" to avoid confusion.
> ---
>  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

Hi, Lucas,

FEC irq cannot wake up CPUs when system is in wait mode. But we can use GPIO_6 for FEC interrupt that GPIO irq wake up CPUs.
No need to disable wait mode as your such patches.

You just config the gpio irq like below patches:
bc20a5d6da71 (ARM: dts: imx6qdl-sabreauto: use GPIO_6 for FEC interrupt.)
6261c4c8f13e (ARM: dts: imx6qdl-sabrelite: use GPIO_6 for FEC interrupt.)


> --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@...gutronix.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__ */
> --
> 2.8.1

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