>>> Li, Shaohua пишет:
>>>> Hi,
>>>> Preempt isn't disabled between ec_burst_enable()/ec_burst_disable(),
>so
>>> it's very likely there is a preemption between them and make the timing
>>> for burst mode not comply with ACPI spec (400ms for first access and
>50ms
>>> for subsequent access).
>>>> We have a system with broken EC and the BIOS engineer identified it's
>>> the timing issue.
>>>> What's the judgment why Linux doesn't comply with ACPI spec?
>>> Please disable ec_burst_* and check again. Judgement is that ec_burst_*
>is
>>> irrelevant to the protocol.
>> What did you about 'irrelevant to the protocol'? This is what the spec
>defines.
>I mean, that EC may drop out of burst mode if timeout happens, and it
>should not change
>the flow of reads and writes to EC (the protocol). More, EC should work
>properly even if
>we do not enter burst mode at all (my suggestion to disable calls to burst
>functions).
>>
>>> What platform and what other symptoms do you have? How exactly this EC
>is
>>> broken?
>> The temperature is wrong when we get it from reading EC. The BIOS
>engineer measured
>> A lot of EC timeout in EC firmware, and they measured the timing how
>Linux accesses
>> EC. The data they captured in oscilloscope shows Linux has long delay to
>access
>> Ec with burst mode enabled, this occurs more often when another
>application is running.
>Do they have any document about implemented EC timeouts? State diagram?
>Other than burst timeout, do they have any other timeouts? What happens if
>they get timeout, do they abort transaction? What do they write in status
>register?
>Do they send GPE? Please collect as much as you can, I was looking for
>such info for a very long time.
They said if burst timeout, then a GPE will fire. OS should check the burst bit in status reg to know if EC is in burst mode. If not, os might reissue burst enable as a retry.
They don't have any document to share with us. If you have other questions, please let me know, but please give detail questions so I can forward them to EC firmware engineer. This is a good chance for us to make EC better.
Thanks,
Shaohua
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