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

[Roger Quadros]

Hi,

On 03/03/2020 21:26, Rob Herring wrote:
> On Tue, Mar 3, 2020 at 8:06 AM Robin Murphy <robin.murphy@xxxxxxx> wrote:
> > On 03/03/2020 8:27 am, Roger Quadros wrote:
> > [...]
> > > > With the patch (in the end). dev->bus_dma_limit is still set to 0 and
> > > > so is not being used.
> > > >
> > > > from of_dma_configure()
> > > >           ret = of_dma_get_range(np, &dma_addr, &paddr, &size);
> > > > ...
> > > >           /* ...but only set bus limit if we found valid dma-ranges
> > > > earlier */
> > > >           if (!ret)
> > > >                   dev->bus_dma_limit = end;
> > > >
> > > > There is no other place bus_dma_limit is set. Looks like every device
> > > > should inherit that
> > > > from it's parent right?
> > >
> > > Any ideas how to expect this to work?
> >
> > Is of_dma_get_range() actually succeeding, or is it tripping up on some
> > aspect of the DT (in which case there should be errors in the log)?

of_dma_get_range() was failing but no errors in the log.

> > Looking again at the fragment below, are you sure it's correct? It
> > appears to me like it might actually be defining a 1-byte-long DMA
> > range, which indeed I wouldn't really expect to work.
>
> Indeed, though it took me a minute to see why.
>
> > Robin.
> >
> > > > diff --git a/arch/arm/boot/dts/dra7.dtsi b/arch/arm/boot/dts/dra7.dtsi
> > > > index 64a0f90f5b52..5418c31d4da7 100644
> > > > --- a/arch/arm/boot/dts/dra7.dtsi
> > > > +++ b/arch/arm/boot/dts/dra7.dtsi
> > > > @@ -680,15 +680,22 @@
> > > >            };
> > > >
> > > >            /* OCP2SCP3 */
> > > > -        sata: sata@4a141100 {
> > > > -            compatible = "snps,dwc-ahci";
> > > > -            reg = <0x4a140000 0x1100>, <0x4a141100 0x7>;
>
> Based on this, the parent address size is 1 cell...
>
> > > > -            interrupts = <GIC_SPI 49 IRQ_TYPE_LEVEL_HIGH>;
> > > > -            phys = <&sata_phy>;
> > > > -            phy-names = "sata-phy";
> > > > -            clocks = <&l3init_clkctrl DRA7_L3INIT_SATA_CLKCTRL 8>;
> > > > -            ti,hwmods = "sata";
> > > > -            ports-implemented = <0x1>;
> > > > +        sata_aux_bus {
> > > > +            #address-cells = <2>;
> > > > +            #size-cells = <2>;
> > > > +            compatible = "simple-bus";
> > > > +            ranges = <0x0 0x0 0x4a140000 0x0 0x1200>;
> > > > +            dma-ranges = <0x0 0x0 0x0 0x0 0x1 0x00000000>;
>
> So this is:
> child addr: 0x0 0x0
> parent addr: 0x0
> size: 0x0 0x1

Good catch.
So I fixed it to

	dma-ranges = <0x0 0x0 0x0 0x1 0x00000000>;

And now it works :).
Thanks!

> The last cell is just ignored I guess if you aren't seeing any errors.
> We check this in dtc for ranges, but not dma-ranges. So I'm fixing
> that.

Great!

> > > > +            sata: sata@4a141100 {
> > > > +                compatible = "snps,dwc-ahci";
> > > > +                reg = <0x0 0x0 0x0 0x1100>, <0x0 0x1100 0x0 0x7>;
> > > > +                interrupts = <GIC_SPI 49 IRQ_TYPE_LEVEL_HIGH>;
> > > > +                phys = <&sata_phy>;
> > > > +                phy-names = "sata-phy";
> > > > +                clocks = <&l3init_clkctrl DRA7_L3INIT_SATA_CLKCTRL 8>;
> > > > +                ti,hwmods = "sata";
> > > > +                ports-implemented = <0x1>;
> > > > +            };
> > > >            };
> > > >
> > > >            /* OCP2SCP1 */

--
cheers,
-roger
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