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2938090556
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>
88 lines
2.0 KiB
C
88 lines
2.0 KiB
C
/*
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* Copyright (C) 2012 Freescale Semiconductor, Inc.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/cpuidle.h>
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#include <linux/module.h>
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#include <asm/cpuidle.h>
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#include "common.h"
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#include "cpuidle.h"
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#include "hardware.h"
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static atomic_t master = ATOMIC_INIT(0);
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static DEFINE_SPINLOCK(master_lock);
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static int imx6q_enter_wait(struct cpuidle_device *dev,
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struct cpuidle_driver *drv, int index)
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{
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if (atomic_inc_return(&master) == num_online_cpus()) {
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/*
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* With this lock, we prevent other cpu to exit and enter
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* this function again and become the master.
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*/
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if (!spin_trylock(&master_lock))
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goto idle;
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imx6_set_lpm(WAIT_UNCLOCKED);
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cpu_do_idle();
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imx6_set_lpm(WAIT_CLOCKED);
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spin_unlock(&master_lock);
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goto done;
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}
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idle:
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cpu_do_idle();
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done:
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atomic_dec(&master);
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return index;
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}
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static struct cpuidle_driver imx6q_cpuidle_driver = {
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.name = "imx6q_cpuidle",
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.owner = THIS_MODULE,
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.states = {
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/* WFI */
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ARM_CPUIDLE_WFI_STATE,
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/* WAIT */
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{
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.exit_latency = 50,
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.target_residency = 75,
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.flags = CPUIDLE_FLAG_TIMER_STOP,
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.enter = imx6q_enter_wait,
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.name = "WAIT",
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.desc = "Clock off",
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},
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},
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.state_count = 2,
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.safe_state_index = 0,
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};
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/*
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* i.MX6 Q/DL has an erratum (ERR006687) that prevents the FEC from waking the
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* CPUs when they are in wait(unclocked) state. As the hardware workaround isn't
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* applicable to all boards, disable the deeper idle state when the workaround
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* isn't present and the FEC is in use.
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*/
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void imx6q_cpuidle_fec_irqs_used(void)
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{
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imx6q_cpuidle_driver.states[1].disabled = true;
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}
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void imx6q_cpuidle_fec_irqs_unused(void)
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{
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imx6q_cpuidle_driver.states[1].disabled = false;
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}
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int __init imx6q_cpuidle_init(void)
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{
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/* Set INT_MEM_CLK_LPM bit to get a reliable WAIT mode support */
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imx6q_set_int_mem_clk_lpm(true);
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return cpuidle_register(&imx6q_cpuidle_driver, NULL);
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}
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