On Fri, 2014-08-22 at 12:54 -0500, Aaron Sierra wrote: > ----- Original Message ----- > > From: "Scott Wood" <scottw...@freescale.com> > > Sent: Thursday, August 21, 2014 5:01:46 PM > > > > On Thu, 2014-08-21 at 16:54 -0500, Aaron Sierra wrote: > > > ----- Original Message ----- > > > > From: "Scott Wood" <scottw...@freescale.com> > > > > Sent: Thursday, August 21, 2014 4:19:56 PM > > > > > > > > Why wouldn't a normal PCI agent be able to bus master? > > > > > > > > -Scott > > > > > > > > > > Short answer: > > > > > > Simply because the hardware strapping for Host/Agent determines the > > > default state of the Bus Master bit in the Command register. Without > > > that bit being set, an Agent won't be able to send the PCI cycles > > > necessary to enumerate the bus. > > > > But what if the host has already set that bit before Linux boots? > > That's a very good point. I think that concern can be addressed by looking > for another telltale sign of enumeration, whether an address has been > assigned to the bridge's BAR 0 (PCSRBAR).
I don't see how that's any different. The host may or may not have assigned an address. > > I understand why you need to do this -- I just don't think this is a > > reliable way of detecting that you're in that situation. How about a > > kernel command line setting? > > I'd like to avoid requiring a kernel command-line option for this. It's hardware description, so you could use a device tree property. -Scott _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
