Skip to main content

Browse the archive

Revision b90d72a6bfdb5e5c62cd223a8cdf4045bfbcb94d authored by Will Deacon on 12 January 2021, 22:18:55 UTC, committed by Catalin Marinas on 13 January 2021, 15:08:41 UTC 
Revert "arm64: Enable perf events based hard lockup detector"
 
This reverts commit 367c820ef08082e68df8a3bc12e62393af21e4b5.

lockup_detector_init() makes heavy use of per-cpu variables and must be
called with preemption disabled. Usually, it's handled early during boot
in kernel_init_freeable(), before SMP has been initialised.

Since we do not know whether or not our PMU interrupt can be signalled
as an NMI until considerably later in the boot process, the Arm PMU
driver attempts to re-initialise the lockup detector off the back of a
device_initcall(). Unfortunately, this is called from preemptible
context and results in the following splat:

  | BUG: using smp_processor_id() in preemptible [00000000] code: swapper/0/1
  | caller is debug_smp_processor_id+0x20/0x2c
  | CPU: 2 PID: 1 Comm: swapper/0 Not tainted 5.10.0+ #276
  | Hardware name: linux,dummy-virt (DT)
  | Call trace:
  |   dump_backtrace+0x0/0x3c0
  |   show_stack+0x20/0x6c
  |   dump_stack+0x2f0/0x42c
  |   check_preemption_disabled+0x1cc/0x1dc
  |   debug_smp_processor_id+0x20/0x2c
  |   hardlockup_detector_event_create+0x34/0x18c
  |   hardlockup_detector_perf_init+0x2c/0x134
  |   watchdog_nmi_probe+0x18/0x24
  |   lockup_detector_init+0x44/0xa8
  |   armv8_pmu_driver_init+0x54/0x78
  |   do_one_initcall+0x184/0x43c
  |   kernel_init_freeable+0x368/0x380
  |   kernel_init+0x1c/0x1cc
  |   ret_from_fork+0x10/0x30

Rather than bodge this with raw_smp_processor_id() or randomly disabling
preemption, simply revert the culprit for now until we figure out how to
do this properly.

Reported-by: Lecopzer Chen <lecopzer.chen@mediatek.com>
Signed-off-by: Will Deacon <will@kernel.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Cc: Sumit Garg <sumit.garg@linaro.org>
Cc: Alexandru Elisei <alexandru.elisei@arm.com>
Link: https://lore.kernel.org/r/20201221162249.3119-1-lecopzer.chen@mediatek.com
Link: https://lore.kernel.org/r/20210112221855.10666-1-will@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
1 parent df06824
Raw File
wm8996.h 
/* SPDX-License-Identifier: GPL-2.0-only */
/*
 * linux/sound/wm8996.h -- Platform data for WM8996
 *
 * Copyright 2011 Wolfson Microelectronics. PLC.
 */

#ifndef __LINUX_SND_WM8996_H
#define __LINUX_SND_WM8996_H

enum wm8996_inmode {
	WM8996_DIFFERRENTIAL_1 = 0,   /* IN1xP - IN1xN */
	WM8996_INVERTING = 1,         /* IN1xN */
	WM8996_NON_INVERTING = 2,     /* IN1xP */
	WM8996_DIFFERENTIAL_2 = 3,    /* IN2xP - IN2xP */
};

/**
 * ReTune Mobile configurations are specified with a label, sample
 * rate and set of values to write (the enable bits will be ignored).
 *
 * Configurations are expected to be generated using the ReTune Mobile
 * control panel in WISCE - see http://www.wolfsonmicro.com/wisce/
 */
struct wm8996_retune_mobile_config {
	const char *name;
	int rate;
	u16 regs[20];
};

#define WM8996_SET_DEFAULT 0x10000

struct wm8996_pdata {
	int irq_flags;  /** Set IRQ trigger flags; default active low */

	int ldo_ena;  /** GPIO for LDO1; -1 for none */

	int micdet_def;  /** Default MICDET_SRC/HP1FB_SRC/MICD_BIAS */

	enum wm8996_inmode inl_mode;
	enum wm8996_inmode inr_mode;

	u32 spkmute_seq;  /** Value for register 0x802 */

	int gpio_base;
	u32 gpio_default[5];

	int num_retune_mobile_cfgs;
	struct wm8996_retune_mobile_config *retune_mobile_cfgs;
};

#endif
back to top