lkml.org 
[lkml]   [2014]   [Oct]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 3/6] pci, thunder: Add PCIe host controller devicetree bindings
On Tue, Oct 07, 2014 at 03:27:44PM +0100, Robert Richter wrote:
> On 24.09.14 18:06:04, Arnd Bergmann wrote:
> > > + compatible = "cavium,thunder-pcie";
> > > + device_type = "pci";
> > > + msi-parent = <&its>;
> > > + bus-range = <0 255>;
> > > + #size-cells = <2>;
> > > + #address-cells = <3>;
> > > + reg = <0x8480 0x00000000 0 0x10000000>; /* Configuration space */
> > > + ranges = <0x03000000 0x8010 0x00000000 0x8010 0x00000000 0x70 0x00000000>, /* mem ranges */
> > > + <0x03000000 0x8300 0x00000000 0x8300 0x00000000 0x80 0x00000000>,
> > > + <0x03000000 0x87e0 0x00000000 0x87e0 0x00000000 0x01 0x00000000>;
> > > + };
> >
> > If you claim the entire 0-255 bus range, I think you should also
> > specify a domain, otherwise it's not predictable which domain you
> > get.
>
> Liviu's code assigns a unique id to the domain if missing, see
> of_pci_get_domain_nr(). So I don't think we need to add a "pci-domain"
> property here.

Not anymore! That function is gone in v12 onwards. What is in -next has
a new function called of_get_pci_domain_nr() (slight name change) but
that only gets the value set in the "linux,pci-domain" property of the
device node. It is the choice of the host bridge driver to use that
function or to use pci_get_new_domain_nr() which *does* generate an
unique id every time it gets called.

>
> Liviu's DT implementation that assigns a unique number differs a bit
> from ACPI which states: "If _SEG [aka domain number] does not exist,
> OSPM assumes that all PCI bus segments are in PCI Segment Group 0."
>
> Maybe of_pci_get_domain_nr() should be similar to ACPI. If there are
> multiple root bridges, the "pci-domain" property could be forced
> instead.

Indeed. But the enforcing is left as an exercise to the host bridge
implementor for the moment.

Best regards,
Liviu

>
> -Robert
>

--
====================
| I would like to |
| fix the world, |
| but they're not |
| giving me the |
\ source code! /
---------------
¯\_(ツ)_/¯

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2014-10-07 17:41    [W:0.537 / U:0.108 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site