[PATCH 06/17] pci: host: pcie-designware: Use *base-mask* for configuring the iATU

Arnd Bergmann arnd at arndb.de
Tue May 6 06:59:00 PDT 2014

On Tuesday 06 May 2014 19:03:52 Kishon Vijay Abraham I wrote:
> In DRA7, the cpu sees 32bit address, but the pcie controller can see only 28bit
> address. So whenever the cpu issues a read/write request, the 4 most
> significant bits are used by L3 to determine the target controller.
> For example, the cpu reserves 0x2000_0000 - 0x2FFF_FFFF for PCIe controller but
> the PCIe controller will see only (0x000_0000 - 0xFFF_FFF). So for programming
> the outbound translation window the *base* should be programmed as 0x000_0000.
> Whenever we try to write to say 0x2000_0000, it will be translated to whatever
> we have programmed in the translation window with base as 0x000_0000.
> Cc: Bjorn Helgaas <bhelgaas at google.com>
> Cc: Marek Vasut <marex at denx.de>
> Signed-off-by: Kishon Vijay Abraham I <kishon at ti.com>
> Acked-by: Jingoo Han <jg1.han at samsung.com>
> Acked-by: Mohit Kumar <mohit.kumar at st.com>

Sorry, but NAK.

We have a standard 'dma-ranges' property to handle this, so use it.

See the x-gene PCIe driver patches for an example. Please also talk
to Santosh about it, as he is implementing generic support for
parsing dma-ranges in platform devices at the moment.

I also suspect you will have to implement swiotlb support to make
generic PCI devices work behind this bridge. Otherwise you end up
with random physical addresses passed into DMA registers.


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