linux-kernel - Re: [PATCH -next] irq-chip/gic-v3-its: Fixed an issue where the ITS executes the residual commands in the queue again when the ITS wakes up from sleep mode.

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Date:   Tue, 17 Nov 2020 21:37:49 +0800
From:   "xuqiang (M)" <xuqiang36@...wei.com>
To:     Marc Zyngier <maz@...nel.org>
CC:     <tglx@...utronix.de>, <linux-kernel@...r.kernel.org>,
        <rui.xiang@...wei.com>
Subject: Re: [PATCH -next] irq-chip/gic-v3-its: Fixed an issue where the ITS
 executes the residual commands in the queue again when the ITS wakes up from
 sleep mode.


在 2020/11/10 17:09, xuqiang (M) 写道:
>
> 在 2020/11/9 18:43, Marc Zyngier 写道:
>> On 2020-11-09 03:05, xuqiang (M) wrote:
>>> 在 2020/11/8 0:54, Marc Zyngier 写道:
>>>> [dropping Jason, whose email address has been bouncing for weeks now]
>>>>
>>>> On 2020-11-07 10:42, Xu Qiang wrote:
>>>>> On my platform, ITS_FLAGS_SAVE_SUSPEND_STATE is not set,thus do 
>>>>> nothing
>>>>
>>>> Which platform?
>>> Hisi Ascend platform
>>>>
>>>>> in its suspend and resuse function.On the other hand,firmware stores
>>>>> GITS_CTRL,GITS_CBASER,GITS_CWRITER and GITS_BASER<n> in the suspend,
>>>>> and restores these registers in the resume. As a result, the ITS 
>>>>> executes
>>>>> the residual commands in the queue.
>>>>
>>>> Which firmware are you using? I just had a look at the trusted 
>>>> firmware source
>>>> code, and while it definitely does something that *looks* like what 
>>>> you are
>>>> describing, it doesn't re-enable the ITS on resume.
>>>>
>>>> So what are you running?
>>>
>>> I am using ATF. Since ITS_FLAGS_SAVE_SUSPEND_STATE is not set,ITS
>>> driver of OS will
>>>
>>> not re-enable ITS in th resume. To make ITS work properly, we changed
>>> the ATF code
>>>
>>> to re-enable ITS on resume.
>>
>> I don't think the words "work properly" apply here.
>>
>> The kernel didn't do what you wanted, so instead of fixing the 
>> kernel, you
>> introduced a bug that results in memory corruption from the firmware.
>>
>> What are you plans to fix your firmware? Because from an upstream ATF
>> compatibility PoV, all there is to do is to fixup the command queue and
>> enable the ITS.
>>
>>         M.
>
>
> I'm sorry I didn't make it clear how to do this. I'm going to reset 
> commit
>
> which re-enable ITS  on the ATF, and drop the checks for 
> ITS_FLAGS_SAVE_SUSPEND_STATE
>
> in the OS.
>
> In other words, the ATF does not re-enable ITS, and OS itself 
> re-enables ITS when it resumes.
>
> To do this, I have to remove the check of ITS_FLAGS_SAVE_SUSPEND_STATE 
> because it is not set.
>
>
> Thanks
>
>         Xu.
>
Hi Marc

     I have been waiting for your reply. Are there any questions about 
this modification plan?

Thanks

         Xu.