Regarding Wake On USB input from S3 Sleep

[Dee Zay]

Hello,

So, is the BIOS handover to the USB stack a prerequisite when resuming from
standby mode HC (not completely off HC)?
In other words, do we need to implement BIOS handover before we can use
wake on usb keyboard input?
Or is there a workaround for this specific functionality?

Many Thanks again,
Julian

On Thu, Feb 11, 2016 at 8:48 PM, Hans Petter Selasky <hps at selasky.org>
wrote:

> On 02/11/16 12:30, Dee Zay wrote:
>
>> Hello,
>>
>> I am a bit confused about the resume problem and its procedures.
>> Could you explain briefly about the difference between resuming from
>> standby(powered) and completely off HC?
>>
>> Thank you,
>> Julian
>>
>
> Hi,
>
> Only the XHCI can resume completely off HC. It knows about which devices
> are enumerated and so on. The other HC's don't.
>
> You need to ensure that filesystem reloads everything when you resume. No
> assumptions can be made about which disk is connected. A USB keyboard is
> simpler, of course.
>
> There is also something called a BIOS, which sometimes enable and
> enumerate the USB devices before the OS is resuming. I think there is a
> standard somewhere how the BIOS can handover enumerated devices to the USB
> stack, but I'm not sure if it is public. In any case FreeBSD will reset the
> HC and start from scratch when resuming. That always works.
>
> --HPS
>