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Date: Sat, 31 Oct 2015 02:35:52 +0800
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Subject: Re: [PATCH v8 1/5] Documentation: add sbsa-gwdt driver documentation
From: Fu Wei <fu.wei@linaro.org>
To: Timur Tabi <timur@codeaurora.org>
Cc: Mark Rutland <mark.rutland@arm.com>,
        Linaro ACPI Mailman List <linaro-acpi@lists.linaro.org>,
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Hi Timur

On 31 October 2015 at 01:46, Timur Tabi <timur@codeaurora.org> wrote:
> On Tue, Oct 27, 2015 at 11:10 PM, Fu Wei <fu.wei@linaro.org> wrote:
>>
>>> Why is WS1 optional?
>>
>> According to the description of WS1 in SBSA 2.3 (5.2 Watchdog Operation) page 21
>> -----------------
>> The signal is fed to a higher agent as an interrupt or reset for it to
>> take executive action.
>> ----------------
>>
>> So WS1 maybe a interrupt.
>>
>> In a real Hardware,  WS1 hooks to a  reset signal pin of BMC, if this
>> pin is triggered, BMC will do a real warm reset.
>> In this case, WS1 is a reset, Linux doesn't need to deal with that.
>>
>> For now , I haven't found a hardware use WS1 as  interrupt.
>> In <ARM v8-A Foundation Platform User Guide> 3.2 Interrupt maps  Page 22
>> Table 3-3 Shared peripheral interrupt assignments
>> IRQ ID       SPI offset      Device
>> 60               28              EL2 Generic Watchdog WS1
>>
>> But I don't have further info about it.
>>
>> Anyway,  because this signal could be interrupt or reset, Linux don't
>> need know this signal sometimes.
>> So I think it should be optional in binding info.
>>
>> Do I miss something? Any suggestion ? Please correct me, thanks.
>
> I think maybe Mark was asking why WS1 is optional, not the WS1

My answer is for "why WS1 is optional"!

> interrupt.  Maybe you can reword the documentation to make is clear
> that

I didn't say : "only the *interrupt* for WS1 is optional."

>
> However, the ACPI table only allows for one interrupt, and it's not
> clear whether that's the WS0 or WS1 interrupt.  So if both WS0 and WS1
> generate an interrupt, how does the driver handle that?

register a interrupt handle for both

>
> --
> Qualcomm Innovation Center, Inc.
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project.



-- 
Best regards,

Fu Wei
Software Engineer
Red Hat Software (Beijing) Co.,Ltd.Shanghai Branch
Ph: +86 21 61221326(direct)
Ph: +86 186 2020 4684 (mobile)
Room 1512, Regus One Corporate Avenue,Level 15,
One Corporate Avenue,222 Hubin Road,Huangpu District,
Shanghai,China 200021