[Qemu-devel] Re: [PATCH 2/2] pci: don't overwrite pci header type.

[Michael S. Tsirkin]

On Wed, Jun 16, 2010 at 07:02:54PM +0000, Blue Swirl wrote:
> On Wed, Jun 16, 2010 at 6:51 PM, Michael S. Tsirkin <address@hidden> wrote:
> > On Wed, Jun 16, 2010 at 06:41:22PM +0000, Blue Swirl wrote:
> >> On Wed, Jun 16, 2010 at 8:54 AM, Michael S. Tsirkin <address@hidden> wrote:
> >> > On Wed, Jun 16, 2010 at 11:20:02AM +0900, Isaku Yamahata wrote:
> >> >> On Tue, Jun 15, 2010 at 12:12:07PM +0300, Michael S. Tsirkin wrote:
> >> >> > On Tue, Jun 15, 2010 at 02:06:46PM +0900, Isaku Yamahata wrote:
> >> >> > > Don't overwrite pci header type.
> >> >> > > Otherwise, multi function bit which pci_init_header_type() sets
> >> >> > > appropriately is lost.
> >> >> > > Anyway PCI_HEADER_TYPE_NORMAL is zero, so it is unnecessary to zero
> >> >> > > which is already zero cleared.
> >> >> > >
> >> >> > > Signed-off-by: Isaku Yamahata <address@hidden>
> >> >> >
> >> >> > ...
> >> >> >
> >> >> > > diff --git a/hw/apb_pci.c b/hw/apb_pci.c
> >> >> > > index 31c8d70..cdf3bc2 100644
> >> >> > > --- a/hw/apb_pci.c
> >> >> > > +++ b/hw/apb_pci.c
> >> >> > > @@ -428,7 +428,8 @@ static int pbm_pci_host_init(PCIDevice *d)
> >> >> > >                   PCI_STATUS_DEVSEL_MEDIUM);
> >> >> > >      pci_config_set_class(d->config, PCI_CLASS_BRIDGE_HOST);
> >> >> > >      pci_set_byte(d->config + PCI_HEADER_TYPE,
> >> >> > > -                 PCI_HEADER_TYPE_NORMAL);
> >> >> > > +                 (pci_get_byte(d->config + PCI_HEADER_TYPE) &
> >> >> > > +                  PCI_HEADER_TYPE_MULTI_FUNCTION) | 
> >> >> > > PCI_HEADER_TYPE_NORMAL);
> >> >> >
> >> >> > what is this doing?
> >> >>
> >> >> It changes the header type to normal device(bit 1-7) without overwriting
> >> >> multi function bit(bit 8).
> >> >
> >> > Don't we know what the multi function bit value is?
> >> >
> >> >> Apb host bridge specifies PCI_HEADER_TYPE_BRIDGE in PCIDeviceInfo,
> >> >> on the other hand pbc_pci_host_init() sets the register
> >> >> to PCI_HEADER_TYPE_NORMAL.
> >> >> To be honest I don't know why it does so, but that is what Blue wants.
> >> >
> >> > BTW I think it would be prettier to have is_bridge instead of header_type
> >> > as a qdev property. Agree?
> >>
> >> Good idea.
> >>
> >> >> So I touch only multi function bit(bit 8) and leave other bit (bit 1-7)
> >> >> unchanged.
> >> >>
> >> >> If you don't like this hunk, I'll drop this hunk and leave it to Blue.
> >> >> What do you think?
> >> >
> >> > Blue Swirl, could you comment on this please?
> >>
> >> I'd go for is_bridge and drop the override for header type in apb_pci.c 
> >> then.
> >
> > Yes, but what header type does it need?
> 
> The type should be bridge (to allow writes to bridge registers), but
> PCI header should use PCI_HEADER_TYPE_NORMAL (because the PBM
> specification says so).

I can no longer get the PBM specs now: are there
alternative links? Need to fix links in code.


> >> >> static PCIDeviceInfo pbm_pci_host_info = {
> >> >>     .qdev.name = "pbm",
> >> >>     .qdev.size = sizeof(PCIDevice),
> >> >>     .init      = pbm_pci_host_init,
> >> >>     .header_type  = PCI_HEADER_TYPE_BRIDGE,   <<<<< Here
> >> >> };
> >> >>
> >> >> --
> >> >> yamahata
> >> >
> >