linux-kernel - Re: [PATCH v4 1/3] ARM: rockchip: fix the CPU soft reset

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Message-ID: <5573DBDC.2010204@rock-chips.com>
Date:	Sun, 07 Jun 2015 13:51:24 +0800
From:	Caesar Wang <wxt@...k-chips.com>
To:	Doug Anderson <dianders@...omium.org>
CC:	Heiko Stuebner <heiko@...ech.de>,
	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	"open list:ARM/Rockchip SoC..." <linux-rockchip@...ts.infradead.org>,
	Russell King <linux@....linux.org.uk>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 1/3] ARM: rockchip: fix the CPU soft reset



在 2015年06月07日 11:43, Doug Anderson 写道:
> Caesar,
>
> On Sat, Jun 6, 2015 at 7:51 PM, Caesar Wang <wxt@...k-chips.com> wrote:
>> @@ -150,13 +159,15 @@ static int __cpuinit rockchip_boot_secondary(unsigned
>> int cpu,
>>                   * sram_base_addr + 4: 0xdeadbeaf
>>                   * sram_base_addr + 8: start address for pc
>>                   * */
>> -               udelay(10);
>> +               udelay(20);
>>
>> I increased the 'udelay(20)' or 'udelay(50)' in rockchip_boot_secondary().
>> Set#2 also can repro this issue over 22600 cycles with testing scripts.
>> (about 1 hours)
>>
>> log:
>> ================= 226 ============
>> [ 4069.134419] CPU1: shutdown
>> [ 4069.164431] CPU2: shutdown
>> [ 4069.204475] CPU3: shutdown
>> ......
>> [ 4072.454453] CPU1: shutdown
>> [ 4072.504436] CPU2: shutdown
>> [ 4072.554426] CPU3: shutdown
>> [ 4072.577827] CPU1: Booted secondary processor
>> [ 4072.582611] CPU2: Booted secondary processor
>> [ 4072.587426] CPU3: Booted secondary processor
>> <hang>
>>
>> The set #4 will be better work.
> OK, I'm OK with this, but I'd like to get Heiko's opinion.
>
> Also:
> * Just for kicks, does mdelay(1) work?  I know that's 100x more than
OK, it should delay more time.

the mdelay(1) can be work over 50000 cycles, so that should be work.


Perhaps, can we use 'usleep_range(500, 1000)' to work.
Heiko, do you agree with it?

> udelay(10), but previously we were actually looping waiting for the
> power domain, right?  ...so maybe the old code used to introduce a
> pretty big delay.
>
> * Does anyone from the chip design team have any idea why patch set #4
> works but patch set #2 doesn't?  I know it's Sunday morning in China
> right now, but maybe you could ask Monday?
>
>
> Thanks!
>
> -Doug
>
>
>

-- 
Thanks,
- Caesar


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