Re: [PATCH 2/3] net: dsa: tag_ocelot_8021q: fix driver dependency

On Thu, Feb 25, 2021 at 4:07 PM Vladimir Oltean [off-list ref] wrote:

On Thu, Feb 25, 2021 at 03:49:08PM +0100, Arnd Bergmann wrote:

quoted

On Thu, Feb 25, 2021 at 3:47 PM Arnd Bergmann [off-list ref] wrote:

quoted

On Thu, Feb 25, 2021 at 3:43 PM Vladimir Oltean [off-list ref] wrote:

quoted

On Thu, Feb 25, 2021 at 03:38:32PM +0100, Arnd Bergmann wrote:

quoted

From: Arnd Bergmann <arnd@arndb.de>

When the ocelot driver code is in a library, the dsa tag

I see the problem now, I should have written 'loadable module', not 'library'.
Let me know if I should resend with a fixed changelog text.

Ah, ok, things clicked into place now that you said 'module'.
So basically, your patch is the standard Kconfig incantation for 'if the
ocelot switch lib is built as module, build the tagger as module too',
plus some extra handling to allow NET_DSA_TAG_OCELOT_8021Q to still be y
or m when COMPILE_TEST is enabled, but it will be compiled in a
reduced-functionality mode, without MSCC_OCELOT_SWITCH_LIB, therefore
without PTP.

Do I get things right? Sorry, Kconfig is a very strange language.

Yes, that's basically correct. I tried to express it in Kconfig the way
I would explain it in English, which means it there are two options:

a) If MSCC_OCELOT_SWITCH_LIB is enabled (y or m) there is
    a direct dependency, so NET_DSA_TAG_OCELOT_8021Q cannot
    be built-in if MSCC_OCELOT_SWITCH_LIB=m
b) When compile-testing *and* MSCC_OCELOT_SWITCH_LIB is fully
    disabled, NET_DSA_TAG_OCELOT_8021Q can be anything (y/m/n)

As a side-effect, this also means that if we are not compile-testing
and MSCC_OCELOT_SWITCH_LIB is disabled, the option is
hdden.

         Arnd.