Re: [PATCH v2 7/8] ARM: dts: r9a06g032: Add the two DMA nodes

[Miquel Raynal <miquel.raynal@bootlin.com>]

Hi Geert,

geert@linux-m68k.org wrote on Wed, 23 Feb 2022 13:54:20 +0100:

> Hi Miquel,
> 
> On Tue, Feb 22, 2022 at 11:35 AM Miquel Raynal
> <miquel.raynal@bootlin.com> wrote:
> > Describe the two DMA controllers available on this SoC.
> >
> > Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>  
> 
> Thanks for your patch!
> 
> > --- a/arch/arm/boot/dts/r9a06g032.dtsi
> > +++ b/arch/arm/boot/dts/r9a06g032.dtsi
> > @@ -184,6 +184,36 @@ nand_controller: nand-controller@40102000 {
> >                         status = "disabled";
> >                 };
> >
> > +               dma0: dma-controller@40104000 {
> > +                       compatible = "renesas,r9a06g032-dma", "renesas,rzn1-dma";
> > +                       reg = <0x40104000 0x1000>;
> > +                       interrupts = <GIC_SPI 56 IRQ_TYPE_LEVEL_HIGH>;
> > +                       clock-names = "hclk";
> > +                       clocks = <&sysctrl R9A06G032_HCLK_DMA0>;  
> 
> power-domains?
> 
> > +                       dma-channels = <8>;
> > +                       dma-requests = <16>;
> > +                       dma-masters = <1>;
> > +                       #dma-cells = <3>;  
> 
> <4>? The dmamux bindings say:
> 
> +      The first four cells are dedicated to the master DMA
> controller. The fifth
> +      cell gives the DMA mux bit index that must be set starting from 0. The
> +      sixth cell gives the binary value that must be written there, ie. 0 or 1.

The DMAC bindings had initially 3 cells, and then received a fourth
optional one. We do not need it here, that's why I'm keeping #dma-cells
to 3.

But on the mux side, I don't want to deal with the presence or absence
of the optional cell so I assumed we would always request 4 cells for
the DMAC to be on the safe side.

Is this assumption wrong?

Thanks,
Miquèl