linux-kernel - Re: [PATCH 2/3] PCI: designware: use untranslated address while programming ATU

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Message-ID: <CAHM4w1mMT5een4pAFb9s1JENm=j1W2yMPYdO+OdBhAy0wcRdjw@mail.gmail.com>
Date:	Thu, 26 Jun 2014 11:07:38 +0530
From:	Pratyush Anand <pratyush.anand@...il.com>
To:	Kishon Vijay Abraham I <kishon@...com>
Cc:	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	linux-doc@...r.kernel.org,
	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
	Jingoo Han <jg1.han@...sung.com>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Mohit KUMAR DCG <mohit.kumar@...com>,
	linux-kernel@...r.kernel.org, grant.likely@...aro.org,
	Jason Gunthorpe <jgunthorpe@...idianresearch.com>,
	Marek Vasut <marex@...x.de>, Arnd Bergmann <arnd@...db.de>,
	Pratyush ANAND <pratyush.anand@...com>
Subject: Re: [PATCH 2/3] PCI: designware: use untranslated address while
 programming ATU

Hi Kishon,

 Few things, if you can help me to understand:

On Wed, Jun 25, 2014 at 11:26 PM, Kishon Vijay Abraham I <kishon@...com> 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.
>
> This is needed when the dt node is modelled something like below
> axi {
>         compatible = "simple-bus";
>         #size-cells = <1>;
>         #address-cells = <1>;
>         ranges = <0x0        0x20000000 0x10000000 // 28-bit bus
>                   0x51000000 0x51000000 0x3000>;
>         pcie@...00000 {
>                 reg = <0x1000 0x2000>, <0x51002000 0x14c>, <0x51000000 0x2000>;
>                 reg-names = "config", "ti_conf", "rc_dbics";

So for DRA7, config base which will be coming from reg property should
be 0x1000 and size 0x2000, no?

>                 #address-cells = <3>;
>                 #size-cells = <2>;
>                 ranges = <0x81000000 0 0          0x03000 0 0x00010000

range type 0x81000000 tells that it is IO

>                           0x82000000 0 0x20013000 0x13000 0 0xffed000>;

range type 0x81000000 tells that it is mem


>         };
> };
>
> Here the CPU address for configuration space is 0x20013000 and the controller
> address for configuration space is 0x13000. The controller address should
be

If above understanding is correct then:

Aren't these addresses(0x20013000  and 0x13000) from mem space
instead of configuration space.

If yes, then how can you get two addresses (CPU and Controller address)
from reg property for configuration space?

~Pratyush
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