On Wed, Mar 9, 2016 at 5:34 PM, Mario Limonciello
<[email protected]> wrote:
>
>
> On 03/07/2016 02:42 PM, Andy Lutomirski wrote:
>> On Mon, Mar 7, 2016 at 12:13 PM, Greg Kroah-Hartman
>> <[email protected]> wrote:
>> I'm adding a couple Dell people.
>>
>> Hi, Dell people-
>>
>> Your latest DSDT has this blatantly buggy method:
>>
>> Method (_Q66, 0, NotSerialized) // _Qxx: EC Query
>> {
>> Acquire (PATM, 0x0064)
>> If ((ECRD != One))
>> {
>> Return (Zero)
>> }
>>
>> NEVT ()
>> Release (PATM)
>> Return (Zero)
>> }
>>
>> At some point during boot (presumably), this runs with ECRD == 0,
>> causing PATM to be acquired and never released. Later on, something
>> involved in USB-C hotplug (I think -- I can occasionally trigger
>> errors during hotplug) breaks when it can't acquire PATM.
>>
>> Could you ask your BIOS team to please add the obviously missing Release
>> (PATM)?
>>
>> I don't know if fixing this bug will solve all the USB-C issues, but
>> it seems unlikely to hurt. I'm going to try to get it to work with a
>> custom method, but I may or may not succeed.
>>
>> --Andy
>>
>>
> Andy,
>
> Sorry I haven't gotten back. I was hoping to have an answer when I
> responded but not yet so just wanted to let you know the message wasn't
> missed.
> I'm inquiring to my team about this. I'm unsure the circumstances that
> the EC isn't ready (race condition?) so it might take some time to get
> answer.
It looks like ECRD is managed entirely in AML like this:
Method (_REG, 2, NotSerialized) // _REG: Region Availability
{
If (((Arg1 == One) == (Arg0 == 0x03)))
{
ECRD = One
ECIN ()
}
If (((Arg1 == Zero) && (Arg0 == 0x03)))
{
ECRD = Zero
}
}
That is also buggy. (((Arg1 == One) == (Arg0 == 0x03))) should be
(((Arg1 == One) && (Arg0 == 0x03))). But that bug goes in the other
direction, so I don't think it explains how this gets triggered.
I've tried to instrument the code, but I haven't found it yet.
--Andy
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