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From: Julien Grall <julien.grall@linaro.org>
To: Oleksandr Tyshchenko <oleksandr.tyshchenko@globallogic.com>
Cc: Stefano Stabellini <stefano.stabellini@eu.citrix.com>,
	Ian Campbell <ian.campbell@citrix.com>,
	"xen-devel@lists.xen.org" <xen-devel@lists.xen.org>
Subject: Re: ARM, time: alternative of using udelay() before init time
Date: Mon, 20 Oct 2014 13:30:17 +0100	[thread overview]
Message-ID: <54450059.1080208@linaro.org> (raw)
In-Reply-To: <CAJEb2DF0DHAkKNG7EPYCTHQk5KCf6M-_2cDkQmw6Neeqw=cPXg@mail.gmail.com>

Hi Oleksandr,

On 10/20/2014 11:12 AM, Oleksandr Tyshchenko wrote:
> On Fri, Oct 17, 2014 at 7:22 PM, Julien Grall <julien.grall@linaro.org> wrote:
>>
>> I'm wondering how Linux deal with the time when the timer is not
>> initialized?
> 
> If I understood correctly the udelay() can works before timer initialized.

I gave a look to the Linux code and it looks like they have an
implementation based on jiffies to used when the timer is not
initialized. (see __loop_udelay in arch/arm/lib/delay.c).

I'm not sure if it's relevant to do exactly the same. But we could
implement a loop-based udelay when the timer is not correctly initialized.

Regards,

-- 
Julien Grall

  reply	other threads:[~2014-10-20 12:30 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-10-16 15:10 ARM, time: alternative of using udelay() before init time Oleksandr Tyshchenko
2014-10-17 12:58 ` Julien Grall
2014-10-17 16:12   ` Oleksandr Tyshchenko
2014-10-17 16:22     ` Julien Grall
2014-10-20 10:12       ` Oleksandr Tyshchenko
2014-10-20 12:30         ` Julien Grall [this message]
2014-10-20 12:35           ` Oleksandr Tyshchenko

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