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To: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Guo Heyi <heyi.guo@linaro.org>,
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From: Marc Zyngier <marc.zyngier@arm.com>
Organization: ARM Ltd
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Date: Thu, 15 Mar 2018 10:02:33 +0000
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Subject: Re: [PATCH v2 1/1] ArmPkg/TimerDxe: Add ISB for timer compare value reload
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On 15/03/18 09:52, Ard Biesheuvel wrote:
> On 15 March 2018 at 09:40, Marc Zyngier <marc.zyngier@arm.com> wrote:
>> On 15/03/18 07:30, Ard Biesheuvel wrote:
>>> On 15 March 2018 at 07:11, Guo Heyi <heyi.guo@linaro.org> wrote:
>>>> Hi Marc and Ard,
>>>>
>>>> I found the timer re-enable code was added by Ard for special reason:
>>>>
>>>> commit b1a633434ddc5fc28de817debd963f7845fb78c7
>>>> Author: Ard Biesheuvel <ard.biesheuvel@linaro.org>
>>>> Date:   Thu Sep 18 21:16:47 2014 +0000
>>>>
>>>>     ArmPkg/TimerDxe: add workaround for KVM timer interrupt handling
>>>>
>>>> So this line of code cannot be removed and I will add an ISB after enabling
>>>> timer.
>>>>
>>>
>>> I'm not sure. IIUC, the KVM issue that required this has been fixed
>>> long ago, and I don't want to carry this forever. Marc?
>>
>> This has been fixed quite a while ago:
>>
>> commit f120cd6533d21075ab103ae6c225b1697853660d
>> Author: Marc Zyngier <marc.zyngier@arm.com>
>> Date:   Mon Jun 23 13:59:13 2014 +0100
>>
>>     KVM: arm/arm64: timer: Allow the timer to control the active state
>>
>>     In order to remove the crude hack where we sneak the masked bit
>>     into the timer's control register, make use of the phys_irq_map
>>     API control the active state of the interrupt.
>>
>>     This causes some limited changes to allow for potential error
>>     propagation.
>>
>>     Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
>>     Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
>>
> 
> Does this mean we can lose this as well?
> 
> https://github.com/tianocore/edk2/blob/master/ArmPkg/Library/ArmGenericTimerVirtCounterLib/ArmGenericTimerVirtCounterLib.c#L31

Indeed, you should be able to remove this as well.

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...