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Date: Thu, 07 Nov 2019 21:34:29 +0100
From: Paul Cercueil <paul@...pouillou.net>
To: Daniel Lezcano <daniel.lezcano@...aro.org>
Cc: Thomas Gleixner <tglx@...utronix.de>, od@...c.me,
linux-kernel@...r.kernel.org,
Maarten ter Huurne <maarten@...ewalker.org>,
Mathieu Malaterre <malat@...ian.org>,
Artur Rojek <contact@...ur-rojek.eu>
Subject: Re: [PATCH] clocksource: Add driver for the Ingenic JZ47xx OST
Le jeu., nov. 7, 2019 at 21:22, Daniel Lezcano
<daniel.lezcano@...aro.org> a écrit :
> On 07/11/2019 20:57, Paul Cercueil wrote:
>>
>>
>> Le jeu., nov. 7, 2019 at 20:39, Daniel Lezcano
>> <daniel.lezcano@...aro.org> a écrit :
>>> On 07/11/2019 16:56, Paul Cercueil wrote:
>>>> Hi Daniel,
>>>>
>>>> On 2019-08-16 16:54, Daniel Lezcano wrote:
>>>>> On 09/08/2019 14:38, Paul Cercueil wrote:
>>>>>> From: Maarten ter Huurne <maarten@...ewalker.org>
>>>>>>
>>>>>> OST is the OS Timer, a 64-bit timer/counter with buffered
>>>>>> reading.
>>>>>>
>>>>>> SoCs before the JZ4770 had (if any) a 32-bit OST; the JZ4770
>>>>>> and
>>>>>> JZ4780 have a 64-bit OST.
>>>>>>
>>>>>> This driver will register both a clocksource and a sched_clock
>>>>>> to the
>>>>>> system.
>>>>>>
>>>>>> Signed-off-by: Maarten ter Huurne <maarten@...ewalker.org>
>>>>>> Signed-off-by: Paul Cercueil <paul@...pouillou.net>
>>>>>> Tested-by: Mathieu Malaterre <malat@...ian.org>
>>>>>> Tested-by: Artur Rojek <contact@...ur-rojek.eu>
>>>>>> ---
>>>>>>
>>>>>
>>>>> [ ... ]
>>>>>
>>>>>> + err = clocksource_register_hz(cs, rate);
>>>>>> + if (err) {
>>>>>> + dev_err(dev, "clocksource registration failed: %d\n",
>>>>>> err);
>>>>>> + clk_disable_unprepare(ost->clk);
>>>>>> + return err;
>>>>>> + }
>>>>>> +
>>>>>> + /* Cannot register a sched_clock with interrupts on */
>>>>>
>>>>> Aren't they already disabled?
>>>>
>>>> Sorry for the late reply.
>>>>
>>>> No, they are not already disabled; this is what I get if I
>>>> comment out
>>>> the local_irq_save()/local_irq_restore():
>>>>
>>>> [ 0.361014] clocksource: ingenic-ost: mask: 0xffffffff
>>>> max_cycles:
>>>> 0xffffffff, max_idle_ns: 159271703898 ns
>>>> [ 0.361515] clocksource: Switched to clocksource ingenic-ost
>>>> [ 0.361686] ------------[ cut here ]------------
>>>> [ 0.361893] WARNING: CPU: 0 PID: 1 at
>>>> kernel/time/sched_clock.c:179
>>>> sched_clock_register+0x7c/0x2e4
>>>> [ 0.362174] CPU: 0 PID: 1 Comm: swapper Not tainted
>>>> 5.4.0-rc5+ #461
>>>> [ 0.362330] Stack : 80744558 80069b44 80770000 00000000
>>>> 00000000
>>>> 00dfd7a7 806e6db4 8106bb74
>>>> [ 0.362619] 806f0000 81067ca4 806f31c7 80769478
>>>> 00000020
>>>> 10000400 8106bb20 00dfd7a7
>>>> [ 0.362906] 00000000 00000000 80780000 00000000
>>>> 00000007
>>>> 00000001 00000049 3563722d
>>>> [ 0.363191] 8106ba61 00000000 ffffffff 00000010
>>>> 806f0000
>>>> 00000000 00000000 806f0000
>>>> [ 0.363477] 00000020 00000000 80714534 80770000
>>>> 00000002
>>>> 80319154 00000000 80770000
>>>> [ 0.363762] ...
>>>> [ 0.363906] Call Trace:
>>>> [ 0.364087] [<8001af14>] show_stack+0x40/0x128
>>>> [ 0.364289] [<8002fd88>] __warn+0xb8/0xe0
>>>> [ 0.364478] [<8002fe14>] warn_slowpath_fmt+0x64/0xc0
>>>> [ 0.364678] [<8072b1c8>] sched_clock_register+0x7c/0x2e4
>>>> [ 0.364895] [<8073c874>] ingenic_ost_probe+0x224/0x248
>>>> [ 0.365090] [<803d5394>] platform_drv_probe+0x40/0x94
>>>> [ 0.365526] [<803d362c>] really_probe+0x104/0x374
>>>> [ 0.365743] [<803d3ff0>] device_driver_attach+0x78/0x80
>>>> [ 0.365938] [<803d4070>] __driver_attach+0x78/0x118
>>>> [ 0.366129] [<803d1700>] bus_for_each_dev+0x7c/0xc8
>>>> [ 0.366318] [<803d226c>] bus_add_driver+0x1bc/0x204
>>>> [ 0.366513] [<803d4878>] driver_register+0x84/0x14c
>>>> [ 0.366717] [<8073a144>] __platform_driver_probe+0x98/0x140
>>>> [ 0.366931] [<80724e38>] do_one_initcall+0x84/0x1b4
>>>> [ 0.367126] [<807250cc>] kernel_init_freeable+0x164/0x240
>>>> [ 0.367318] [<805df75c>] kernel_init+0x10/0xf8
>>>> [ 0.367510] [<8001542c>] ret_from_kernel_thread+0x14/0x1c
>>>> [ 0.367722] ---[ end trace 7fedf00408fa3bed ]---
>>>> [ 0.367985] sched_clock: 32 bits at 12MHz, resolution 83ns,
>>>> wraps
>>>> every 178956970966ns
>>>>
>>>> At kernel/time/sched_clock.c:179 there is:
>>>> WARN_ON(!irqs_disabled());
>>>
>>> That is strange, no drivers is doing that and no warning is
>>> appearing.
>>>
>>> Isn't missing a local_irq_disable in the code path in the stack
>>> above?
>>
>> I think it comes to the fact that the other drivers are probed much
>> earlier in the boot process, while this one is probed as a regular
>> platform device driver.
>
>
> There are other drivers doing and nobody is disabling the interrupt:
>
> em_sti.c:static struct platform_driver em_sti_device_driver = {
> ingenic-timer.c:static struct platform_driver ingenic_tcu_driver = {
> sh_cmt.c:static struct platform_driver sh_cmt_device_driver = {
> sh_mtu2.c:static struct platform_driver sh_mtu2_device_driver = {
> sh_tmu.c:static struct platform_driver sh_tmu_device_driver = {
> timer-ti-dm.c:static struct platform_driver omap_dm_timer_driver = {
Yes, but they don't register a sched_clock at all (except for
ingenic-timer, but it does probe using TIMER_OF_DECLARE), and this
warning is in sched_clock_register().
>
>>>>>> + local_irq_save(flags);
>>>>>> + if (soc_info->is64bit)
>>>>>> + sched_clock_register(ingenic_ost_read_cntl, 32, rate);
>>>>>> + else
>>>>>> + sched_clock_register(ingenic_ost_read_cnth, 32, rate);
>>>>>> + local_irq_restore(flags);
>>>>>> +
>>>>>> + return 0;
>>>>>> +}
>>>>>> +
>>>
>>>
>>> --
>>> <http://www.linaro.org/> Linaro.org │ Open source software for
>>> ARM SoCs
>>>
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>>>
>>
>>
>
>
> --
> <http://www.linaro.org/> Linaro.org │ Open source software for ARM
> SoCs
>
> Follow Linaro: <http://www.facebook.com/pages/Linaro> Facebook |
> <http://twitter.com/#!/linaroorg> Twitter |
> <http://www.linaro.org/linaro-blog/> Blog
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