Re: [PATCH v3 2/2] mtd: rawnand: ingenic: Limit MTD_NAND_JZ4780 to architecture only

Paul Cercueil
2020-07-26T16:06:26Z

Le sam. 25 juil. 2020 à 20:30, Arnd Bergmann <arnd@arndb.de> a écrit :
> On Sat, Jul 25, 2020 at 2:17 PM Paul Cercueil <paul@crapouillou.net>
> wrote:
>> Le ven. 24 juil. 2020 à 17:54, Krzysztof Kozlowski
>> <krzk@kernel.org> a
>> écrit :
>> > On Fri, Jul 24, 2020 at 05:50:06PM +0200, Paul Cercueil wrote:
>> >> Le ven. 24 juil. 2020 à 17:33, Krzysztof Kozlowski
>> >> <krzk@kernel.org> a écrit:
>> >> > On Fri, 24 Jul 2020 at 17:19, Paul Cercueil
>> <paul@crapouillou.net>
>> >> > wrote:
>> >>
>> >> On MIPS, the SoC selection is a Kconfig "choice", so you can
>> only
>> >> support
>> >> one SoC family, unfortunately.
>> >
>> > Let's say someone selected then some other architecture
>> > (MIPS_ALCHEMY).
>> > They could select this MTD driver.
>> >
>> > Does it mean they would be able to run it on Ingenic hardware?
>>
>> In *theory* yes, as long as the Kconfig options that MACH_INGENIC
>> selects are enabled, the kernel should boot and work on Ingenic
>> SoCs.
>
> Right now, this won't work yet, because there are platform specific
> functions that are implemented by each of the platforms in arch/mips,
> e.g. arch/mips/generic/init.c and arch/mips/jz4740/setup.c.
>
> A lot of the newer platforms are part of arch/mips/generic
> (CONFIG_MIPS_GENERIC), which roughly corresponds to
> CONFIG_ARCH_MULTIPLATFORM on in arch/arm/.
> Similarly, there are header files in arch/mips/include/asm/mach-*/
> that conflict and you need to have the right one.
>
> To have more than one platform enabled, each one needs to
> have all of that platform code converted to fit into the
> MIPS_GENERIC framework. This can be a lot of work, but
> I suppose the ingenic platform would be a candidate for
> which this makes sense, as long as new SoCs of that family
> still come out.

It should be much less work now that the vast majority of
arch/mips/jz4740 is gone. The code left is pretty much generic. I can
have a look to convert it to the MIPS_GENERIC framework.

Although the code there is scary. Have a look at
arch/mips/include/asm/{machine,mips_machine}.h, you'll see what I mean.

Anyway, I think we're way past the scope of this patch, so for this one:
Acked-by: Paul Cercueil <paul@crapouillou.net>

Cheers,
-Paul