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91740fc824
In the current cpuidle implementation for i.MX6q, the CPU that sets
'WAIT_UNCLOCKED' and the CPU that returns to 'WAIT_CLOCKED' are always
the same. While the CPU that sets 'WAIT_UNCLOCKED' is in IDLE state of
"WAIT", if the other CPU wakes up and enters IDLE state of "WFI"
istead of "WAIT", this CPU can not wake up at expired time.
Because, in the case of "WFI", the CPU must be waked up by the local
timer interrupt. But, while 'WAIT_UNCLOCKED' is set, the local timer
is stopped, when all CPUs execute "wfi" instruction. As a result, the
local timer interrupt is not fired.
In this situation, this CPU will wake up by IRQ different from local
timer. (e.g. broacast timer)
So, this fix changes CPU to return to 'WAIT_CLOCKED'.
Signed-off-by: Kohji Okuno <okuno.kohji@jp.panasonic.com>
Fixes: e5f9dec8ff ("ARM: imx6q: support WAIT mode using cpuidle")
Cc: <stable@vger.kernel.org>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
85 lines
2.0 KiB
C
85 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 <soc/imx/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 int num_idle_cpus = 0;
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static DEFINE_SPINLOCK(cpuidle_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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spin_lock(&cpuidle_lock);
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if (++num_idle_cpus == num_online_cpus())
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imx6_set_lpm(WAIT_UNCLOCKED);
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spin_unlock(&cpuidle_lock);
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cpu_do_idle();
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spin_lock(&cpuidle_lock);
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if (num_idle_cpus-- == num_online_cpus())
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imx6_set_lpm(WAIT_CLOCKED);
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spin_unlock(&cpuidle_lock);
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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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EXPORT_SYMBOL_GPL(imx6q_cpuidle_fec_irqs_used);
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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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EXPORT_SYMBOL_GPL(imx6q_cpuidle_fec_irqs_unused);
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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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imx6_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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