Re: [PATCH v2 2/6] dt-bindings: spi: Document Renesas SPIBSC bindings

[Geert Uytterhoeven <geert@linux-m68k.org>]

Hi Sergei,

On Tue, Dec 10, 2019 at 9:07 PM Sergei Shtylyov
<sergei.shtylyov@cogentembedded.com> wrote:
> On 12/09/2019 05:09 PM, Geert Uytterhoeven wrote:
> >> Document the bindings used by the Renesas SPI bus space controller.
> >> Signed-off-by: Chris Brandt <chris.brandt@renesas.com>
> >> ---
> >> v2:
> >>  * change to YAML format
> >>  * add interrupts property
> >>  * Used more terms directly from the hardware manual
> >
> > Thanks for the update!
> >
> >> --- /dev/null
> >> +++ b/Documentation/devicetree/bindings/spi/renesas,spibsc.yaml
> [...]
> >> +properties:
> >> +  compatible:
> >> +    oneOf:
> >> +      - items:
> >> +          - enum:
> >> +              - renesas,r7s72100-spibsc     # RZ/A1
> >> +              - renesas,r7s9210-spibsc      # RZ/A2
> >> +
> >> +  reg:
> >> +    minItems: 2
> >> +    maxItems: 2
> >> +    items:
> >> +      - description: Registers
> >> +      - description: Memory Mapped Address Space
> >
> > The second one is not needed, if you would add "ranges" for the
> > memory-mapped mode.
>
>    I'm not sure we can do that. The flash bus is accessed via a window
> with the high bits in the DREAR reg, even in the direct read mode...

So if the FLASH is too large, you cannot access all of it without
programming the high bits.
However, when using XIP,  you're limited to the window size anyway.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds