Re: PCI bus numbering and orphaned devices

In message: <20030609210919.33379_at_hydrogen.funkthat.com>
            John-Mark Gurney <gurney_j_at_efn.org> writes:
: > > +#ifdef __sparc64__
: > > +		/*
: > > +		 * XXX - some sparc hardware has valid hardware when the
: > > +		 * function 0 doesn't probe.  Scan all functions.
: > > +		 */
: > > +		pcifunchigh = PCI_FUNCMAX;
: > > +#else
: > >  		pcifunchigh = 0;
: > > +#endif
: > >  		for (f = 0; f <= pcifunchigh; f++) {
: > >  			dinfo = pci_read_device(pcib, busno, s, f, dinfo_size);
: > >  			if (dinfo != NULL) {
: > 
: > This is problematic as it ignores the fact about single function
: > devices which may react to all function numbers.
: 
: Wouldn't this happen with the current logic? since if function 0 is
: found, it scans the rest...  (Might be getting confused with SCSI
: buses).

Actually, there's no reason not to scan the hardware.  we likely
should be checking the multi function status differently than we are
right now.  We also shouldn't be rejecting based on the vendor id.
while that provides a convenient way to chek to see if it really isn't
there, a better sanity check would be to check the header type to see
if it a one we know about (0, 1 or 2).  If so, then we know if the
device is there.  that might be a better hueristic to see if we need
to scan everything.

: Actually, I was thinking that we could check to see if the next word
: is not -1.  The chip responds to the rest of the registers, but just
: doesn't respond to the DEVVENDOR (first word).

since header type is a required field, this likely is a better way to
go.  maybe keep the test against -1 for adding it as a child, but
don't assume nothing is there unless the header type is bogus.

: I'm also thinking of adding support code to the pci bus to let the
: userland add a new device node to be probed.  It shouldn't be too hard,
: but would be help in these cases.

I'd rather tht we fix the pci probe code to do the right thing.
Kludges like this tend to live for a long time because nobody bothers
to fix them correctly...

I'm thinking that the loop should be more like:

		pcifunchigh = 0;
		f = 0;
		hdrtype	= REG(PCIR_HEADERTYPE, 1);
		if (hdrtype & 0x7f > 2)
			continue;
		if (hdrtype & 0x80)
			pcifunchigh = PCI_FUNCMAX;
		for (f = 0; f <= pcifunchigh; f++) {
			dinfo = pci_read_device(pcib, busno, s, f, dinfo_size);
			if (dinfo != NULL)
				pci_add_child(dev, dinfo);
		}

might be better code (REG likely needs to be correctly defined for
this context).

this is based on my limited understanding that function 0 shouldn't be
attached and function 1 should...

Warner