From: Roger Quadros <rogerq@ti.com> To: Robin Murphy <robin.murphy@arm.com>, Rob Herring <robh+dt@kernel.org> Cc: "Christoph Hellwig" <hch@lst.de>, "Péter Ujfalusi" <peter.ujfalusi@ti.com>, "Murali Karicheri" <m-karicheri2@ti.com>, "Nori, Sekhar" <nsekhar@ti.com>, "Anna, Suman" <s-anna@ti.com>, "Stefan Wahren" <stefan.wahren@i2se.com>, "Andreas Färber" <afaerber@suse.de>, "Hans Verkuil" <hverkuil@xs4all.nl>, devicetree@vger.kernel.org, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, "Nishanth Menon" <nm@ti.com>, "hdegoede@redhat.com" <hdegoede@redhat.com>, "Vignesh Raghavendra" <vigneshr@ti.com> Subject: Re: dma_mask limited to 32-bits with OF platform device Date: Wed, 19 Feb 2020 17:40:48 +0200 [thread overview] Message-ID: <f69835e3-61fd-ec63-1bee-2d69747d106d@ti.com> (raw) In-Reply-To: <827fa19d-1990-16bc-33f5-fc82ac0d4a8a@arm.com> On 19/02/2020 17:25, Robin Murphy wrote: > On 19/02/2020 2:29 pm, Roger Quadros wrote: >> Rob, >> >> On 18/02/2020 19:22, Rob Herring wrote: >>> On Tue, Feb 18, 2020 at 2:28 AM Roger Quadros <rogerq@ti.com> wrote: >>>> >>>> Chrishtoph, >>>> >>>> The branch works fine for SATA on DRA7 with CONFIG_LPAE once I >>>> have the below DT fix. >>>> >>>> Do you intend to send these fixes to -stable? >>>> >>>> ------------------------- arch/arm/boot/dts/dra7.dtsi ------------------------- >>>> index d78b684e7fca..853ecf3cfb37 100644 >>>> @@ -645,6 +645,8 @@ >>>> sata: sata@4a141100 { >>>> compatible = "snps,dwc-ahci"; >>>> reg = <0x4a140000 0x1100>, <0x4a141100 0x7>; >>>> + #size-cells = <2>; >>>> + dma-ranges = <0x00000000 0x00000000 0x1 0x00000000>; >>> >>> dma-ranges should be in the parent (bus) node, not the device node. >> >> I didn't understand why. >> >> There are many devices on the parent bus node and all devices might not have the 32-bit DMA limit >> the SATA controller has. >> >> SATA controller is the bus master and the ATA devices are children of the SATA controller. > > But SATA is not a memory-mapped bus - in the context of MMIO, the AHCI is the bus-master device, not a bridge or level of interconnect. The DeviceTree spec[1] clearly defines dma-ranges as an address translation between a "parent bus" and a "child bus". > > If in the worst case this address-limited interconnect really only exists between the AHCI's master interface and everything else in the system, then you'll have to describe it explicitly to meet DT's expectation of a "bus" (e.g. [2]). Yes, it's a bit clunky, but any scheme has its edge cases. I understand now. Thanks. > >> From Documentation/devicetree/booting-without-of.txt >> >> * DMA Bus master >> Optional property: >> - dma-ranges: <prop-encoded-array> encoded as arbitrary number of triplets of >> (child-bus-address, parent-bus-address, length). Each triplet specified >> describes a contiguous DMA address range. >> The dma-ranges property is used to describe the direct memory access (DMA) >> structure of a memory-mapped bus whose device tree parent can be accessed >> from DMA operations originating from the bus. It provides a means of >> defining a mapping or translation between the physical address space of >> the bus and the physical address space of the parent of the bus. >> (for more information see the Devicetree Specification) >> >> * DMA Bus child >> Optional property: >> - dma-ranges: <empty> value. if present - It means that DMA addresses >> translation has to be enabled for this device. > > Disregarding that this was apparently never in ePAPR, so not grandfathered in to DTSpec, and effectively nobody ever has actually followed it (oh, if only...), note "<empty>" - that still doesn't imply that a *non-empty* dma-ranges would be valid on device nodes. > > Robin. > > [1] https://www.devicetree.org/specifications/ > [2] https://lore.kernel.org/lkml/20181010120737.30300-20-laurentiu.tudor@nxp.com/ -- cheers, -roger Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki. Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki
next prev parent reply other threads:[~2020-02-19 15:41 UTC|newest] Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-02-12 10:49 Roger Quadros 2020-02-12 11:37 ` Robin Murphy 2020-02-12 12:33 ` Roger Quadros 2020-02-12 14:04 ` Robin Murphy 2020-02-12 17:57 ` Christoph Hellwig 2020-02-17 13:21 ` Christoph Hellwig 2020-02-17 14:54 ` Peter Ujfalusi 2020-02-18 7:26 ` Peter Ujfalusi 2020-02-18 8:28 ` Roger Quadros 2020-02-18 17:22 ` Rob Herring 2020-02-19 14:29 ` Roger Quadros 2020-02-19 15:25 ` Robin Murphy 2020-02-19 15:40 ` Roger Quadros [this message] 2020-02-26 11:33 ` Roger Quadros 2020-03-03 8:27 ` Roger Quadros 2020-03-03 14:06 ` Robin Murphy 2020-03-03 19:26 ` Rob Herring 2020-03-04 8:28 ` Roger Quadros
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=f69835e3-61fd-ec63-1bee-2d69747d106d@ti.com \ --to=rogerq@ti.com \ --cc=afaerber@suse.de \ --cc=devicetree@vger.kernel.org \ --cc=hch@lst.de \ --cc=hdegoede@redhat.com \ --cc=hverkuil@xs4all.nl \ --cc=linux-kernel@vger.kernel.org \ --cc=m-karicheri2@ti.com \ --cc=nm@ti.com \ --cc=nsekhar@ti.com \ --cc=peter.ujfalusi@ti.com \ --cc=robh+dt@kernel.org \ --cc=robin.murphy@arm.com \ --cc=s-anna@ti.com \ --cc=stefan.wahren@i2se.com \ --cc=vigneshr@ti.com \ --subject='Re: dma_mask limited to 32-bits with OF platform device' \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: link
This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox; as well as URLs for NNTP newsgroup(s).