Re: [PATCH v2] hw/usb/vt82c686-uhci-pci: Use ISA instead of PCI interrupts

[Gerd Hoffmann]

On Mon, Oct 11, 2021 at 12:31:17PM +0200, BALATON Zoltan wrote:
> On Mon, 11 Oct 2021, Gerd Hoffmann wrote:
> > On Tue, Oct 05, 2021 at 03:12:05PM +0200, BALATON Zoltan wrote:
> > > This device is part of a superio/ISA bridge chip and IRQs from it are
> > > routed to an ISA interrupt set by the Interrupt Line PCI config
> > > register. Change uhci_update_irq() to allow this and use it from
> > > vt82c686-uhci-pci.
> > 
> > Hmm, shouldn't this logic be part of the superio bridge emulation?
> 
> But how? The ISA bridge does not know about PCI and PCI does not know about
> ISA. UHCI is a PCIDevice and would raise PCI interrupts. Where and how could
> I convert that to ISA interrupts? (Oh and ISA in QEMU is not Qdev'ified and
> I don't want to do that as it's too much work and too much to break that I
> can't even test so if an alternative solution involves that then get
> somebody do that first.) This patch puts the irq mapping in the vt82xx
> specific vt82c686-uhci-pci.c which in the real chip also contains the ISA
> bridge so in a way it's part of the superio bridge emulation in that this
> uhci variant is part of that chip model.

I'd suggest to first switch over uhci to use pci_allocate_irq() +
qemu_set_irq() (see ehci for example).

With that in place it should be possible to have vt82c686-uhci-pci.c
create a different IRQ setup without changes elsewhere in uhci and
without adding extra callbacks.

HTH,
  Gerd