Re: [Xen-devel] [PATCH 3/4] xen: set the right flags when enabling interrupts for 8250

[Julien Grall <julien.grall@xxxxxxxxxx>]

On 07/26/2013 04:31 AM, Chen Baozi wrote:
> 
> On Jul 26, 2013, at 9:14 AM, Chen Baozi <baozich@xxxxxxxxx> wrote:
> 
>>
>> On Jul 25, 2013, at 8:33 PM, Julien Grall <julien.grall@xxxxxxxxxx> wrote:
>>
>>> On 07/25/2013 12:31 PM, Chen Baozi wrote:
>>>>
>>>> On Jul 25, 2013, at 7:17 PM, Julien Grall <julien.grall@xxxxxxxxxx> 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?
>>
>> I could see clocks.c/clocks.o in its u-boot sources, but I don't think 
>> U-boot has already enabled it, for I could read such lines from Linux kernel 
>> boot messages:

Are you trying to boot Linux on bare metal or as dom0?

>> """
>> OMAP clockevent source: GPTIMER1 at 32768 Hz
>> sched_clock: 32 bits at 32kHz, resolution 30517ns, wraps every 131071999s
>> OMAP clocksource: 32k_counter at 32768 Hz
>> arch_timer: No interrupt available, giving up

Do you have a "arm,armv7-timer" compatible node in your DTS with
interrupts? Here Linux can't find an appropriate interrupt.

>> omap5_realtime_timer_init: arch_timer_register failed -22
>>
>>>
>>> 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?
>>
>> Yes, TI has published an 49.6MB Technical Reference Manual online with 88 
>> pages section about timer.
> 
> Wait. I think I might make a mistake. The "arch timer" is different from 
> "timer" as devices, right? The timer section in Technical Reference Manual 
> seems to be the latter one, for it is  connect to the Level-4 interconnect of 
> OMAP5432 and described as "ti,omap5430-timer" in DTS. I think the "arch 
> timer" you mentioned should refer to "arm,armv7-timer", right?

By "arch timer" I mean "arm,armv7-timer".

-- 
Julien

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