Re: dma_mask limited to 32-bits with OF platform device

[Roger Quadros]

Rob,

On 18/02/2020 19:22, Rob Herring wrote:
> On Tue, Feb 18, 2020 at 2:28 AM Roger Quadros <rogerq@xxxxxx> 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.

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.
- dma-coherent: Present if dma operations are coherent



> >                          interrupts = <GIC_SPI 49 IRQ_TYPE_LEVEL_HIGH>;
> >                          phys = <&sata_phy>;
> >                          phy-names = "sata-phy";
> >
> >
> > cheers,
> > -roger
> >
> > On 17/02/2020 15:21, Christoph Hellwig wrote:
> > > Roger,
> > >
> > > can you try the branch below and check if that helps?
> > >
> > >       git://git.infradead.org/users/hch/misc.git arm-dma-bus-limit
> > >
> > > Gitweb:
> > >
> > >       http://git.infradead.org/users/hch/misc.git/shortlog/refs/heads/arm-dma-bus-limit
> >
> > --
> > Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
> > Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki

--
cheers,
-roger
Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki