Re: Minor xhci issues (failed to peer) on Dell XPS 13 9350 (Skylake)

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On 03/07/2016 02:42 PM, Andy Lutomirski wrote:
> On Mon, Mar 7, 2016 at 12:13 PM, Greg Kroah-Hartman
> <gregkh@xxxxxxxxxxxxxxxxxxx> 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.

The most likely thing to resolve USB-C issues is to update your alpine
ridge firmware.  A lot of the same USB-C issues are present on Windows
but fixed in AR firmware updates.
This unfortunately can't be done yet in Linux or even in an EFI
environment like we do with UEFI capsules.

I know that sucks, and I am working to solve that problem separately.
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