From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kishon Vijay Abraham I Subject: Re: [PATCH 06/17] pci: host: pcie-designware: Use *base-mask* for configuring the iATU Date: Wed, 14 May 2014 20:34:10 +0530 Message-ID: <537385EA.2070302@ti.com> References: <1399383244-14556-1-git-send-email-kishon@ti.com> <4528185.oZbgyuuFKX@wuerfel> <537302CD.7000701@ti.com> <5281007.CFRjW0Yeu2@wuerfel> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <5281007.CFRjW0Yeu2@wuerfel> Sender: linux-doc-owner@vger.kernel.org To: Arnd Bergmann Cc: Jingoo Han , 'Santosh Shilimkar' , devicetree@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-omap@vger.kernel.org, linux-pci@vger.kernel.org, rogerq@ti.com, balajitk@ti.com, 'Bjorn Helgaas' , 'Marek Vasut' List-Id: devicetree@vger.kernel.org Hi Arnd, On Wednesday 14 May 2014 06:15 PM, Arnd Bergmann wrote: > On Wednesday 14 May 2014 11:14:45 Kishon Vijay Abraham I wrote: >> hi Arnd, >> >> On Tuesday 13 May 2014 07:04 PM, Arnd Bergmann wrote: >>> On Tuesday 13 May 2014 15:27:46 Arnd Bergmann wrote: >>>> On Tuesday 13 May 2014 18:56:23 Kishon Vijay Abraham I wrote: >>>>>> If you have a case where the outbound translation is a 256MB (i.e. 28bit) >>>>>> section of the CPU address space, that could be represented as >>>>>> >>>>>> ranges = <0x82000000 0 0 0xb0000000 0 0x10000000>; >>>>>> >>>>>> or >>>>>> >>>>>> ranges = <0x82000000 0 0xb0000000 0xb0000000 0 0x10000000>; >>>>>> >>>>>> depending on whether you want the BARs to be programmed using a low >>>>>> address 0x0-0x0fffffff or an address matching the window >>>>>> 0xb0000000-0xbfffffff. >>>>> >>>>> The problem is, for configuring the window starting at 0xb0000000, the ATU >>>>> should be programmed 0x0000000 (the cpu address for it will be 0xb0000000 though). >>>>> >>>> >>>> Then use the first of the two? >>>> >>> >>> To clarify: using <0x82000000 0 0 0xb0000000 0 0x10000000> will give you >>> a mem_offset of 0xb0000000, which should work just fine for this case. >>> >>> What I don't understand is why the ATU cares about whether the outbound >>> address is 0x0000000 or 0xb0000000 if it just decodes the lower 28 bit >>> anyway. Did you mean that we have to program the BARs using low addresses >>> regardless of what is programmed in the ATU? That would make more sense, >>> and it also matches what I suggested. >> >> No, It's not like it decodes only the lower 28bits. The BARs is programmed with >> 32 bit value. >> >> My pcie dt node has >> ranges = <0x00000800 0 0x20001000 0x20001000 0 0x00002000 /* CONFIG */ >> 0x81000000 0 0 0x20003000 0 0x00010000 /* IO */ >> 0x82000000 0 0x20013000 0x20013000 0 0xffed000>; /* MEM */ >> >> Consider MEM address space.. >> >> Here both PCI address and CPU address is 0x20013000. So when there is a write >> to cpu addr 0x20013000 [writel(virt_addr(0x20013000)], we want it to be >> translated to PCI addr 0x20013000. So in 'ATU', we would expect *base* to be >> programmed to *0x20013000* and target to be programmed to *0x20013000*. But >> that's not the case for DRA7xx. For DRA7xx *base* should be programmed to >> *0x0013000* and target should be programmed to *0x20013000*. > > Ok, got it, thanks for your patience. > > I think this would best be modeled as a separate bus node that contains the > restriction, like this: > > / { > #address-cells = <1>; // or <2> if you support > 4GB address space > #size-cells = <1>; > > soc { > #address-cells <1>; > #size-cells = <1>; > ranges; > dma-ranges; > > ... // all normal devices > > axi@20000000 { > #size-cells = <1>; > #address-cells = <1>; > dma-ranges; // can access all 4GB outbound > ranges = <0 0x20000000 0x10000000>; // 28-bit bus > > pci@0 { > reg = <0x0 0x1000>, // internal regs > <0x1000 0x2000>; // config space > dma-ranges; // 32-bit outbound > ranges = <0x81000000 0 0 0x3000 0 0x00010000 /* IO */ > 0x82000000 0 0x20013000 0x13000 0 0xffed000>; /* MEM */ > }; > }; > }; > }; Nice :-) Thanks Kishon