Hi Krzysztof,

On Tue, May 25, 2021 at 2:04 PM Krzysztof Kozlowski
[off-list ref] wrote:

On 24/05/2021 08:39, Dmitry Osipenko wrote:

quoted

24.05.2021 11:54, Geert Uytterhoeven пишет:

quoted

On Mon, May 24, 2021 at 1:26 AM Dmitry Osipenko [off-list ref] wrote:

quoted

There are couple older platforms that can't be compile-tested because they
partially implement CLK API. It causes build failure of kernel drivers due
to the missing symbols of the unimplemented part of CLK API.

These platforms are: ARM EP93XX, ARM OMAP1, m68k ColdFire, MIPS AR7,
                     MIPS Ralink.

Disable compile-testing for HAVE_LEGACY_CLK=y.

Reported-by: kernel test robot <redacted>
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>

Thanks for your patch!

quoted

--- a/init/Kconfig
+++ b/init/Kconfig

@@ -131,7 +131,7 @@ config INIT_ENV_ARG_LIMIT

 config COMPILE_TEST
        bool "Compile also drivers which will not load"
-       depends on HAS_IOMEM
+       depends on HAS_IOMEM && !HAVE_LEGACY_CLK

That sounds a bit drastic to me.  Usually we just try to implement the
missing functionality, or provide stubs.
Which functions are missing?

Everything that belongs to CONFIG_COMMON_CLK needs stubs.

That is everything under CONFIG_HAVE_CLK [1], excluding functions
belonging to clk-devres.o and clk-bulk.o [2]. The HAVE_LEGACY_CLK
selects HAVE_CLK, but the COMMON_CLK is under HAVE_CLK too.

[1]
https://elixir.bootlin.com/linux/v5.13-rc3/source/include/linux/clk.h#L786
[2]
https://elixir.bootlin.com/linux/v5.13-rc3/source/drivers/clk/Makefile#L3

This problem is repeated over and over again for the past years. Some
maintainers are adding "depends on COMMON_CLK" for COMPILE_TEST of each
driver, but this doesn't solve the root of the problem, and thus, it's
constantly reoccurring.

Recently Krzysztof Kozlowski added couple more clk stubs for MIPS, but
still lots of stubs are missing. Some platforms don't have any stubs at
all and apparently nobody cares to fix them.

There 3 possible solutions:

1. Factor out COMMON_CLK from HAVE_LEGACY_CLK, if this is possible
2. Build stubs universally, maybe using weak functions.

I vote for this one - global stubs.

Yep.

Or for a new one:
4. Disable COMPILE_TEST for specific platforms (mentioned in commit
msg). Eventually could be like:
config RALINK
        depends !COMPILE_TEST || (COMPILE_TEST && COMMON_CLK)

That's a neat idea!

Of course there's a fifth option:

5. Convert legacy platforms to COMMON_CLK.

Which is already happening for ARM EP93XX.

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