Re: [PATCH v2] spi: orion: support armada extended baud rates

[Greg Ungerer <gerg-JBU5SbJe1FlAfugRpC6u6w@public.gmane.org>]

Hi Geert,

On 05/09/14 17:36, Geert Uytterhoeven wrote:
> Hi Greg,
>
> On Fri, Sep 5, 2014 at 2:36 AM, Greg Ungerer <gerg-JBU5SbJe1FlAfugRpC6u6w@public.gmane.org> wrote:
>>> Are the Orion rates and register bits a subset of the Armada ones?
>>> I.e. does the Armada work with the Orion setup?
>> The bits used by the orion are a subset (bits 0-4 of the SPI
>> configuration register) of those used by the armada (bits 0-4 and
>> 6-7).
>>
>> In practice the defined prescalar values for the orion do give
>> the same divisor for the same bits set on armada. The extra bits
>> on the armada let you get to lower SPI baudrates (which is more of
>> a problem on the armada with its higher core clocks).
> OK, so the answer is yes.
>
>>>> This change introduces a new device tree compatible device name
>>>> "armada-spi". This is used in place of "orion-spi" on the Armada SoC
>>>> parts.
>>>> -                               compatible = "marvell,orion-spi";
>>>> +                               compatible = "marvell,armada-spi";
>>> If the answer to my above question is yes, you want to keep
>>> "marvell,orion-spi" as a fallback.
>> Do you mean like this?
>>
>>    compatible = "marvell,orion-spi", "marvell,armada-spi";
> No, the other way around (from most-specific to least-specific):
>
>      compatible = "marvell,armada-spi", "marvell,orion-spi"
>
> So the Armada version is used if available, and the Orion version
> is used as a fallback.

Ok, got it. Thanks.

Regards
Greg


> Gr{oetje,eeting}s,
>
>                          Geert
>
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert-Td1EMuHUCqxL1ZNQvxDV9g@public.gmane.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
>

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