From: arnd@arndb•de (Arnd Bergmann)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH v2 07/10] ARM: tegra: pcie: Add device tree support
Date: Fri, 22 Jun 2012 13:03:21 +0000 [thread overview]
Message-ID: <201206221303.21985.arnd@arndb.de> (raw)
In-Reply-To: <20120622124311.GA21606@avionic-0098.mockup.avionic-design.de>
On Friday 22 June 2012, Thierry Reding wrote:
> On Fri, Jun 22, 2012 at 05:46:52AM -0600, Bjorn Helgaas wrote:
> > On Fri, Jun 22, 2012 at 5:00 AM, Thierry Reding
> > <thierry.reding@avionic-design•de> wrote:
> > >> Is the bus number aperture included somewhere? How do we know what
> > >> bus numbers are available for allocation under each bridge?
> > >
> > > Not yet. I don't think DT imposes a bus number allocation on PCI
> > > bridges. However the matching of DT nodes to PCI bridges is done based
> > > on the bus number. For that you provide a bus-ranges property which
> > > defines the bus aperture of the given PCI bridge. The DT matching code
> > > compares the first cell of this property with the primary bus number of
> > > the bridge.
> >
> > I don't fully understand this, but I can tell you that things don't
> > work very well if we don't know the aperture. We can make
> > assumptions, like the root bus is 00, and then enumerate everything
> > reachable from there. But then all we know is the largest bus number
> > actually reachable from bus 00, which is usually smaller then the end
> > of the aperture. We don't know how many unused bus numbers there are
> > in the aperture, so we can't safely allocate any for hot-added
> > devices.
I believe the assumption today is that all bus numbers are ok on each
root port, which is usually the case. There was something about a Power
Mac that faked a single PCI bus number space across both an AGP and
a PCIe domain in pmac_pci_fixup_u4_of_node(), but I think that is the
exception.
Is there any requirement to use a bus aperture on non-PC hardware?
> I think DT support for PCI is lacking in a lot of areas. PowerPC seems
> to be the only architecture actively setting up busses according to the
> bus-range property specified in the DT. All other architectures seem to
> not pre-allocate bus apertures and go with the default instead. From
> what you say that means hot-plugging is out. Although I don't think the
> Tegra PCIe controller even supports hot-plugging.
If the default is allowing any bus numbers, and that matches the
hardware capabilities, I think hot-plugging would work.
Arnd
next prev parent reply other threads:[~2012-06-22 13:03 UTC|newest]
Thread overview: 96+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-06-11 15:05 [PATCH v2 00/10] ARM: tegra: Add PCIe device tree support Thierry Reding
2012-06-11 15:05 ` [PATCH v2 01/10] PCI: Keep pci_fixup_irqs() around after init Thierry Reding
2012-06-11 15:05 ` [PATCH v2 02/10] ARM: pci: Keep pci_common_init() " Thierry Reding
2012-06-11 15:05 ` [PATCH v2 03/10] ARM: pci: Allow passing per-controller private data Thierry Reding
2012-06-11 15:05 ` [PATCH v2 04/10] ARM: tegra: Move tegra_pcie_xclk_clamp() to PMC Thierry Reding
2012-06-11 15:05 ` [PATCH v2 05/10] ARM: tegra: Rewrite PCIe support as a driver Thierry Reding
2012-06-11 21:09 ` Stephen Warren
2012-06-12 6:41 ` Thierry Reding
2012-06-12 7:24 ` Thierry Reding
2012-06-12 16:00 ` Stephen Warren
2012-06-13 8:12 ` Thierry Reding
2012-06-11 21:22 ` Stephen Warren
2012-06-12 4:59 ` Thierry Reding
2012-06-11 15:05 ` [PATCH v2 06/10] ARM: tegra: pcie: Add MSI support Thierry Reding
2012-06-11 21:19 ` Stephen Warren
2012-06-12 5:07 ` Thierry Reding
2012-06-12 5:33 ` Stephen Warren
2012-06-12 5:41 ` Thierry Reding
2012-06-12 6:10 ` Thierry Reding
2012-06-12 15:40 ` Stephen Warren
2012-06-12 17:23 ` Thierry Reding
2012-06-11 15:05 ` [PATCH v2 07/10] ARM: tegra: pcie: Add device tree support Thierry Reding
2012-06-11 21:33 ` Stephen Warren
2012-06-12 6:21 ` Thierry Reding
2012-06-12 15:44 ` Stephen Warren
2012-06-12 17:20 ` Thierry Reding
2012-06-12 19:10 ` Mitch Bradley
2012-06-12 19:46 ` Stephen Warren
2012-06-12 19:52 ` Mitch Bradley
2012-06-13 5:54 ` Thierry Reding
2012-06-13 7:04 ` Mitch Bradley
2012-06-12 20:15 ` Stephen Warren
2012-06-12 21:11 ` Mitch Bradley
2012-06-13 6:45 ` Thierry Reding
2012-06-13 7:28 ` Mitch Bradley
2012-06-13 7:52 ` Thierry Reding
2012-06-13 8:05 ` Mitch Bradley
2012-06-13 8:19 ` Thierry Reding
2012-06-13 8:36 ` Mitch Bradley
2012-06-13 8:42 ` Thierry Reding
2012-06-14 9:19 ` Thierry Reding
2012-06-14 18:30 ` Stephen Warren
2012-06-14 19:29 ` Thierry Reding
2012-06-14 19:50 ` Stephen Warren
2012-06-15 6:12 ` Thierry Reding
2012-06-19 13:30 ` Thierry Reding
2012-06-19 16:40 ` Stephen Warren
2012-06-19 21:31 ` Mitch Bradley
2012-06-20 16:32 ` Stephen Warren
2012-06-20 17:41 ` Mitch Bradley
2012-06-20 17:47 ` Stephen Warren
2012-06-20 19:57 ` Arnd Bergmann
2012-06-20 20:19 ` Mitch Bradley
2012-06-21 6:47 ` Thierry Reding
2012-06-22 10:18 ` Bjorn Helgaas
2012-06-22 11:00 ` Thierry Reding
2012-06-22 11:46 ` Bjorn Helgaas
2012-06-22 12:43 ` Thierry Reding
2012-06-22 13:03 ` Arnd Bergmann [this message]
2012-06-22 16:49 ` Bjorn Helgaas
2012-06-22 16:53 ` Arnd Bergmann
2012-06-22 17:13 ` Bjorn Helgaas
2012-06-22 21:08 ` Arnd Bergmann
2012-06-22 17:14 ` Arnd Bergmann
2012-06-22 17:00 ` Stephen Warren
2012-06-22 17:28 ` Stephen Warren
2012-06-23 21:35 ` Bjorn Helgaas
2012-06-25 6:34 ` Thierry Reding
2012-06-26 17:22 ` Stephen Warren
2012-06-27 6:19 ` Thierry Reding
2012-06-22 16:20 ` Stephen Warren
2012-06-22 17:09 ` Mitch Bradley
2012-06-22 11:04 ` Thierry Reding
2012-06-22 13:22 ` Thierry Reding
2012-06-22 13:48 ` Arnd Bergmann
2012-06-22 14:02 ` Thierry Reding
2012-06-22 16:40 ` Arnd Bergmann
2012-06-13 20:21 ` Arnd Bergmann
2012-06-14 8:37 ` Thierry Reding
2012-06-14 10:25 ` Arnd Bergmann
2012-06-14 10:31 ` Thierry Reding
2012-06-14 11:06 ` Arnd Bergmann
2012-06-14 11:58 ` Thierry Reding
2012-06-13 6:34 ` Thierry Reding
2012-06-13 16:20 ` Stephen Warren
2012-06-13 17:03 ` Stephen Warren
2012-06-11 15:05 ` [PATCH v2 08/10] ARM: tegra: harmony: Initialize regulators from DT Thierry Reding
2012-06-11 21:36 ` Stephen Warren
2012-06-12 6:13 ` Thierry Reding
2012-06-21 20:17 ` Stephen Warren
2012-06-22 6:06 ` Thierry Reding
2012-06-11 15:05 ` [PATCH v2 09/10] ARM: tegra: harmony: Initialize PCIe " Thierry Reding
2012-06-11 21:41 ` Stephen Warren
2012-06-12 5:48 ` Thierry Reding
2012-06-12 15:38 ` Stephen Warren
2012-06-11 15:05 ` [PATCH v2 10/10] ARM: tegra: trimslice: " Thierry Reding
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