Re: Usefulness of CONFIG_MACH_JZ47*

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Le mar., sept. 20 2022 at 14:31:38 +0200, H. Nikolaus Schaller <hns@xxxxxxxxxxxxx> a écrit :
Hi Paul,

 Am 20.09.2022 um 11:09 schrieb Paul Cercueil <paul@xxxxxxxxxxxxxxx>:

 Hi Nikolaus,

Le mar., sept. 20 2022 at 08:31:30 +0200, H. Nikolaus Schaller <hns@xxxxxxxxxxxxx> a écrit :
 Hi Paul,
it seems as if there aren't many places left over where the MACH_JZ47* configs are still in use:
 drivers/char/hw_ramdom/Kconfig
 drivers/clk/ingenic/Kconfig
 drivers/gpu/drm/ingenic/Kconfig
 drivers/pinctrl/pinctrl-ingenic.c
Is it possible to get rid of them and just have CONFIG_MACH_INGENIC_GENERIC?
 This might simplify my defconfig for multiple machines.

 CONFIG_MIPS_GENERIC_KERNEL=y

This breaks compilation for me, e.g.

arch/mips/mm/cache.c:203:6: error: 'cpu_has_tx39_cache' undeclared (first use in this function)

v6.0-rc does not have 'cpu_has_tx39_cache' anywhere in that file, or in arch/mips/ for that matter. It was removed in v5.18.

And a v5.17 kernel compiles fine here with these options enabled. So it's a problem on your side, I guess.

 CONFIG_BOARD_INGENIC=y

This config option does not exist (at least in v6.0-rc). Probably you refer to CONFIG_INGENIC_GENERIC_BOARD.

No, I do not, and yes, it exists.

As far as I see, this does not choose to build any device tree blob.

I tried some patch to get the .dtb built, but the resulting kernel does not show any activity.

If I e.g. switch back from CONFIG_INGENIC_GENERIC_BOARD=y to CONFIG_JZ4780_CI20=y the kernel works.

Because in the first case you build a generic kernel, which does not embed any .dtb, and you are responsible for providing the kernel with the blob at boot time; while if you build with CONFIG_JZ4780_CI20=y it embeds the .dtb inside the kernel.

You can embed the .dtb into the generic kernel at compile-time too, have a look at "Kernel type -> Kernel appended dtb support." Not sure why you'd want that for a generic kernel, though.


Then you can support all Ingenic-based boards alongside other MIPS boards.

Yes, I know, but why are the MACH_JZ47* not replaced by CONFIG_MACH_INGENIC_GENERIC if they are almost unused or completely removed?

They *are* used.

BTW: there are also seems to be some board specific CONFIGs in processor specific code (e.g. CONFIG_JZ4780_CI20 in irqchip code).

rgrep CI20 drivers/irqchip/

returns nothing for me.

So selecting a MACH is not sufficient to get these features.

All this looks a little fragile and incomplete... Maybe if I find some time (which is unfortunately quite unlikely) I can propose some fixes.

It is not "fragile and incomplete", it works as intended, and it's a feature I use often.

-Paul






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