From mboxrd@z Thu Jan  1 00:00:00 1970
From: Julien Grall <julien.grall@linaro.org>
Subject: Re: [PATCH 3/4] xen: set the right flags when enabling
 interrupts for 8250
Date: Thu, 25 Jul 2013 13:33:28 +0100
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To: Chen Baozi <baozich@gmail.com>
Cc: Keir Fraser <keir@xen.org>, Ian Campbell <Ian.Campbell@citrix.com>, xen-devel@lists.xen.org
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On 07/25/2013 12:31 PM, Chen Baozi wrote:
> 
> On Jul 25, 2013, at 7:17 PM, Julien Grall <julien.grall@linaro.org> wrote:
> 
>> On 07/25/2013 10:14 AM, Chen Baozi wrote:
>>
>>> Besides this test, I noticed that we set a timer to poll UART after enabling
>>> the interrupt. And the timer initialization codes are platform specific, which
>>> should be implemented in xen/arch/arm/platforms/omap5.c for example. However,
>>> I haven't done this yet. (I used to plan to turn to this work after UART porting
>>> has been done.) Is it a possible factor that may cause my issues?
>>
>> Xen uses the arch timers to handle the time. On some platform (for
>> instance the Arndale), it's not enabled by default.
>>
>> If the omap5 boot with the arch timers enabled, you don't need to
>> implement the init_time callback.
>>
>> Do you know if Xen receives timer interrupts?
> 
> Any way that I could confirm this?
> 
> There is a line of boot message:
> 
> "Using generic timer at 0 KHz."
> 

It seems the arch timer is not configured/enabled. Do you know if U-boot
enables it?

It's not clear to me, how you need to implement init_time. Do you have a
datasheet with the board? If yes, is there a section for the section timer?

Perhaps the good start is linux/arch/arm/mach-omap2/timer.c.

-- 
Julien