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Date:   Mon, 20 Aug 2018 07:31:53 -0700
From:   Tony Lindgren <tony@atomide.com>
To:     Kishon Vijay Abraham I <kishon@ti.com>
Cc:     Rob Herring <robh+dt@kernel.org>, Nishanth Menon <nm@ti.com>,
        Santosh Shilimkar <ssantosh@kernel.org>,
        Will Deacon <will.deacon@arm.com>,
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        <linux-arm-kernel@lists.infradead.org>,
        Vignesh R <vigneshr@ti.com>, Tero Kristo <t-kristo@ti.com>,
        Russell King <linux@armlinux.org.uk>,
        Sudeep Holla <sudeep.holla@arm.com>
Subject: Re: Re: [RFC PATCH 5/6] arm64: dts: ti: Add Support for AM654 SoC
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* Kishon Vijay Abraham I <kishon@ti.com> [180808 06:35]:
> On Tuesday 05 June 2018 07:35 PM, Rob Herring wrote:
> > Really need 64-bit addresses and sizes? Use ranges to limit the
> > address space if possible.
> 
> We now have address-cells as <1>,
> https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/arch/arm64/boot/dts/ti/k3-am65.dtsi#n49
> 
> However each PCIe instance has 2 data regions and one of the regions
> (PCIE0_CORE_CORE_DAT_SLV_PCIE_DAT1/PCIE1_CORE_CORE_DAT_SLV_PCIE_DAT1 specified
> in the "MAIN Domain Memory Map" table of TRM http://www.ti.com/lit/pdf/spruid7)
> is above the 32bit region and requires 2 cells to specify the start address.
> This region is used to access MEM_SPACE of PCIe endpoint when operating in root
> complex mode and access memory of PCI root complex when operating in endpoint mode.
> 
> In order to describe this, should we change the address-cells back to <2> or do
> you suggest any other alternatives?

It's probably best to have the top level cbass interconnect use
#size-cells = <2> and then have it's child interconnects have
#size-cells = <1> if they don't need ranges above 4GB.

BTW, what's the difference between all these three similar PCIE
ranges?

PCIE0_CORE_CORE_DAT_SLV_PCIE_CORE 0x0005500000 0x0005600000 1 MB
PCIE1_CORE_CORE_DAT_SLV_PCIE_CORE 0x0005600000 0x0005700000 1 MB

PCIE0_CORE_CORE_DAT_SLV_PCIE_DAT0 0x0010000000 0x0018000000 128 MB
PCIE1_CORE_CORE_DAT_SLV_PCIE_DAT0 0x0018000000 0x0020000000 128 MB

PCIE0_CORE_CORE_DAT_SLV_PCIE_DAT1 0x4000000000 0x4100000000 4 GB
PCIE1_CORE_CORE_DAT_SLV_PCIE_DAT1 0x4100000000 0x4200000000 4 GB

Regards,

Tony