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Re: [Qemu-devel] [patch 0/2] USB UHCI global suspend / remote wakeup
From: |
Paul Brook |
Subject: |
Re: [Qemu-devel] [patch 0/2] USB UHCI global suspend / remote wakeup |
Date: |
Fri, 26 Nov 2010 12:09:47 +0000 |
User-agent: |
KMail/1.13.5 (Linux/2.6.36-trunk-amd64; KDE/4.4.5; x86_64; ; ) |
> On 11/26/10 03:15, Marcelo Tosatti wrote:
> > On Fri, Nov 26, 2010 at 12:38:28AM +0000, Paul Brook wrote:
> >>> This patch enables USB UHCI global suspend/resume feature. The OS will
> >>> stop the HC once all ports are suspended. If there is activity on the
> >>> port(s), an interrupt signalling remote wakeup will be triggered.
> >>
> >> I'm pretty sure this is wrong. Suspend/resume works based on physical
> >> topology, i.e. the resume notification should go to the the port/hub to
> >> which the device is connected, not directly to the host controller.
> >
> > You are correct in that USB HUB emulation does not propagate resume, but
> > this does not make this patch incorrect.
>
> Well, it does. When the notification is port based our software model
> should better reflect that, so we have the chance to add resume
> propagation to the hub emulation later on.
Exactly. The patch assumes the device is connected to a root hub port. This
assumption is incorrect.
The device should be sending the resume signal to the port/hub to which it is
connected. If that hub is still active it will reactivate the port, and flag a
port change notification in the normal manner. If the hub is also suspended it
will propagate the resume notification upstream (which may or may not be the
root hub).
Paul
- [Qemu-devel] PATCH: QEMU support for UHCI suspend / remote wake up, Marcelo Tosatti, 2010/11/25
- [Qemu-devel] Re: PATCH: QEMU support for UHCI suspend / remote wake up, Gerd Hoffmann, 2010/11/25
- [Qemu-devel] [patch 0/2] USB UHCI global suspend / remote wakeup, Marcelo Tosatti, 2010/11/25
- [Qemu-devel] [patch 2/2] support for UHCI suspend / remote wake up, Marcelo Tosatti, 2010/11/25
- [Qemu-devel] [patch 1/2] add USBBusOps to USBBus, Marcelo Tosatti, 2010/11/25
- Re: [Qemu-devel] [patch 0/2] USB UHCI global suspend / remote wakeup, Paul Brook, 2010/11/25
- Re: [Qemu-devel] [patch 0/2] USB UHCI global suspend / remote wakeup, Marcelo Tosatti, 2010/11/25
- Re: [Qemu-devel] [patch 0/2] USB UHCI global suspend / remote wakeup, Gerd Hoffmann, 2010/11/26
- Re: [Qemu-devel] [patch 0/2] USB UHCI global suspend / remote wakeup,
Paul Brook <=