Re: [PATCH/RFC] spi: sh-msiof: Fix MSIOF address for DMAC

[Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>]

Hi Kaneko-san, Kataoka-san,

On Sun, Mar 15, 2015 at 3:36 PM, Yoshihiro Kaneko <ykaneko0929@xxxxxxxxx> wrote:
> From: Ryo Kataoka <ryo.kataoka.wt@xxxxxxxxxxx>
>
> MSIOF Base Address H'E6xx can be accessed by CPU and DMAC.
> MSIOF Base Address H'E7xx for DMAC was removed from H/W manual.

"Address 0xE7xx can be accesses only from DMA." was indeed removed.
However, "Note: Address H'E6xx can be accessed only by CPU." is still
there in the latest version of the R-Car Gen2 manual I have (v1.01).
Presumably all of this was copied from another SoC (see below)?

MSIOF DMA seems to work fine on my Koelsch (R-Car M2-W ES1.0) with this patch
(and the DTS changes) applied, though.

> Signed-off-by: Ryo Kataoka <ryo.kataoka.wt@xxxxxxxxxxx>
> Signed-off-by: Yoshihiro Kaneko <ykaneko0929@xxxxxxxxx>
> ---
>
> Hi Geert-san,
>
> I have also found patches to address this problem in DTS files
> which seems to be a good way to handle this problem. I plan to send
> them separately. I'm unsure if this driver change is also appropriate.

If there really exist no SoCs where the DMA engine has to access a different
register set than the CPU, then it can be removed from the driver, and from
the binding docs in Documentation/devicetree/bindings/spi/sh-msiof.txt.

However, according to the manuals, SH-Mobile AG5 (sh73a0), R-Mobile APE6
(r8a73a4), and R-Mobile A1 (r8a7740) also have MSIOF blocks with two register
banks?

Thanks!

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx

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
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