RE: [PATCH v3 2/4] usb: aspeed-vhub: fix remote wakeup failure in iKVM use case

[Neal Liu]

> -----Original Message-----
> From: Neal Liu
> Sent: Monday, December 20, 2021 10:23 AM
> To: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>; Felipe Balbi
> <balbi@xxxxxxxxxx>; Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>; Joel
> Stanley <joel@xxxxxxxxx>; Andrew Jeffery <andrew@xxxxxxxx>; Cai Huoqing
> <caihuoqing@xxxxxxxxx>; Tao Ren <rentao.bupt@xxxxxxxxx>; Julia Lawall
> <julia.lawall@xxxxxxxx>; kernel test robot <lkp@xxxxxxxxx>; Sasha Levin
> <sashal@xxxxxxxxxx>; linux-usb@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
> linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; linux-aspeed@xxxxxxxxxxxxxxxx
> Cc: BMC-SW <BMC-SW@xxxxxxxxxxxxxx>
> Subject: RE: [PATCH v3 2/4] usb: aspeed-vhub: fix remote wakeup failure in
> iKVM use case
> 
> > -----Original Message-----
> > From: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
> > Sent: Tuesday, December 14, 2021 10:36 AM
> > To: Neal Liu <neal_liu@xxxxxxxxxxxxxx>; Felipe Balbi
> > <balbi@xxxxxxxxxx>; Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>;
> > Joel Stanley <joel@xxxxxxxxx>; Andrew Jeffery <andrew@xxxxxxxx>; Cai
> > Huoqing <caihuoqing@xxxxxxxxx>; Tao Ren <rentao.bupt@xxxxxxxxx>; Julia
> > Lawall <julia.lawall@xxxxxxxx>; kernel test robot <lkp@xxxxxxxxx>;
> > Sasha Levin <sashal@xxxxxxxxxx>; linux-usb@xxxxxxxxxxxxxxx;
> > linux-kernel@xxxxxxxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx;
> > linux-aspeed@xxxxxxxxxxxxxxxx
> > Cc: BMC-SW <BMC-SW@xxxxxxxxxxxxxx>
> > Subject: Re: [PATCH v3 2/4] usb: aspeed-vhub: fix remote wakeup
> > failure in iKVM use case
> >
> > On Thu, 2021-12-09 at 02:37 +0000, Neal Liu wrote:
> > > I'm confused. Signaling Wakeup when wakeup_en is set if it has any
> > > ep activities is not exactly what you said?
> > >
> > > wakeup_en is set only if host allows this device have wakeup
> > > capability and bus being suspended.
> > >
> > > Normal ep activities would not write the MMIO because wakeup_en is
> > > not set.
> >
> > Hrm... I didn't think wakeup_en was limited to the bus being
> > suspended, but maybe I misremember, it's been a while.
> >
> > Cheers,
> > Ben.
> >
> 
> wakeup_en is only set in the case of host set USB_DEVICE_REMOTE_WAKEUP
> feature to vhub devices.
> I think this behavior only occurs during host is going to suspend, and set this
> feature to any device which can wakeup itself before sleep.
> Thanks
> 
> -Neal
> 
Would you like to test it if you have some free time.
Please feel free for any feedback.

-Neal