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Date: Tue, 27 Sep 2011 16:09:57 +0300
From: "Michael S. Tsirkin" <mst@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH qemu] e1000: CTRL.RST emulation
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To: Peter Maydell <peter.maydell@linaro.org>
Cc: Anthony Liguori <aliguori@us.ibm.com>, Dean Nelson <dnelson@redhat.com>, qemu-devel@nongnu.org, Jesse Brandeburg <jesse.brandeburg@intel.com>, Aurelien Jarno <aurelien@aurel32.net>, Alex Williamson <alex.williamson@redhat.com>, Jeff Kirsher <jeffrey.t.kirsher@intel.com>, Kevin Wolf <mail@kevin-wolf.de>, Andy Gospodarek <andy@greyhouse.net>

On Tue, Sep 27, 2011 at 01:39:17PM +0100, Peter Maydell wrote:
> On 27 September 2011 13:32, Michael S. Tsirkin <mst@redhat.com> wrote:
> > On Tue, Sep 27, 2011 at 12:50:21PM +0100, Peter Maydell wrote:
> >> On 27 September 2011 12:25, Michael S. Tsirkin <mst@redhat.com> wrote:
> >> > e1000 spec says CTRL.RST write should have the same effect
> >> > as bus reset, except that is preserves PCI Config.
> >> > Reset device registers and interrupts.
> >> >
> >> > Fix suggested by Andy Gospodarek <andy@greyhouse.net>
> >>
> >> Doesn't this have the same effect as this patch:
> >> http://patchwork.ozlabs.org/patch/108673/
> >
> > Right except mine clears the interrupts as well.
> 
> I agree that's required, but why doesn't it belong in
> e1000_reset() ?

I think not, because pci core resets interrupts for us.

> Surely a qdev reset ought also to clear
> the output irq signals...
> [Disclaimer: this is fishing for somebody to explain to
> me what the semantics of qdev reset actually are :-)]

AFAIK what happens is that the qdev is only involved
until we get to the pci root. From then on
pci_bus_reset calls pci_device_reset to reset the device.

> > I missed that patch - what happened to it in the end?
> 
> I think it just got lost in the shuffle (Anthony L never
> did come back and actually produce a compiler that gave
> a warning on it, so I think that was just a misremembering
> on his part.)
> 
> -- PMM

Yes, that just looks strange. So I intend to just stick this
patch in my tree, unless someone NACKs. Then it'll get merged
in due course.

-- 
MST