From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Hellstrom Date: Fri, 20 May 2011 14:22:33 +0000 Subject: Re: [PATCH 0/2] sparc32,leon: PCI patches Message-Id: <4DD67929.6040905@gaisler.com> List-Id: References: <4DB68838.1020304@gaisler.com> In-Reply-To: <4DB68838.1020304@gaisler.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: sparclinux@vger.kernel.org David Miller wrote: >From: Daniel Hellstrom >Date: Fri, 20 May 2011 10:01:11 +0200 > > > >>David Miller wrote: >> >> >> >>>From: Daniel Hellstrom >>>Date: Thu, 19 May 2011 15:13:14 +0200 >>> >>> >>> >>> >>>>The PowerPC for example assign resources >>>>(arch/powerpc/kernel/pci-common.c), and PowerPC may also have a >>>>OpenBoot loader: >>>> >>>> >>>> >>>On some powerpc systems, like sparc64 Niagara, you can't blindly go >>>poking around the PCI config space at all and must rely completely >>>and entirely upon the OpenBoot device tree. >>> >>> >>> >>I see, that may be because IRQ routing or resource allocation is done >>in a non-standard way I guess, perhaps because of bugs on some of the >>motherboards. >> >> > >Or because PCI accesses have to go through a hypervisor. > > Aaah. Its a pity sparc32 doesn't have a hypervisor, we could do really cool stuff with that. >The point is that having it all setup in OpenBoot is a great >abstraction because you don't have to care. > >It also allows things like being able to disable devices with things >like "pcia-probe-list" and "pcib-probe-list" properties in the PCI >host controller node, which we end up honoring on sparc64 simply >because we never directly probe PCI space to probe devices. > > I agree that it is a better solution in that case and in other cases too. The problem will be for me to write a PCI Library in the limited context of the PROM, it is much more complex that writing a PCI host driver. The non-free PCI specification alone is heavy, compatibility between PCI revisions and then there is the bridge specification... ugg, I will probably have to leave that to the next generation :) Daniel