Re: [PATCH v2 0/2] PCI: Add support for PCI Enhanced Allocation "BARs"

[David Daney <ddaney.cavm@gmail.com>]

Hi Sean,

Thanks for doing this, I think we will use it for Cavium ThunderX.  A 
couple of questions...


On 09/23/2015 03:27 PM, Sean O. Stalley wrote:
> PCI Enhanced Allocation is a new method of allocating MMIO & IO
> resources for PCI devices & bridges. It can be used instead
> of the traditional PCI method of using BARs.
>
> EA entries are hardware-initialized to a fixed address.
> Unlike BARs, regions described by EA are cannot be moved.
> Because of this, only devices which are permanently connected to
> the PCI bus can use EA. A removable PCI card must not use EA.
>
> This patchset adds support for using EA entries instead of BARs
> on Root Complex Integrated Endpoints.
>
> The Enhanced Allocation ECN is publicly available here:
> https://www.pcisig.com/specifications/conventional/ECN_Enhanced_Allocation_23_Oct_2014_Final.pdf
>
>
> Changes from V1:
> 	- Use generic PCI resource claim functions (instead of EA-specific functions)
> 	- Only add support for RCiEPs (instead of all devices).

Why not all devices?  The spec. allows for EA on devices behind bridges.


> 	- Removed some debugging messages leftover from early testing.
>
>
> Sean O. Stalley (2):
>    PCI: Add Enhanced Allocation register entries
>    PCI: Add support for Enhanced Allocation devices
>
>   drivers/pci/pci.c             | 174 ++++++++++++++++++++++++++++++++++++++++++
>   drivers/pci/pci.h             |   1 +
>   drivers/pci/probe.c           |   3 +
>   include/uapi/linux/pci_regs.h |  40 +++++++++-
>   4 files changed, 217 insertions(+), 1 deletion(-)
>