[PATCH v2] of: OF_IRQ: select IRQ_DOMAIN instead of depending on it

[Randy Dunlap <rdunlap@infradead.org>]

IRQ_DOMAIN is a hidden (not user visible) symbol. Users cannot set
it directly thru "make *config", so drivers should select it instead
of depending on it if they need it.
Relying on it being set for a dependency is risky.

Consistently using "select" or "depends on" can also help reduce
Kconfig circular dependency issues.

Therefore, change OF_IRQ's use of "depends on" to "select".

This patch reduces one Kconfig circular dependency in
drivers/mux/Kconfig when MUX_MMIO attempts to select REGMAP (a failed
patch), which that driver needs (but does not completely resolve that
issue). [1]

before this patch: (10 lines of detail)
drivers/net/ethernet/arc/Kconfig:19:error: recursive dependency detected!
drivers/net/ethernet/arc/Kconfig:19:	symbol ARC_EMAC_CORE is selected by ARC_EMAC
drivers/net/ethernet/arc/Kconfig:26:	symbol ARC_EMAC depends on OF_IRQ
drivers/of/Kconfig:81:	symbol OF_IRQ depends on IRQ_DOMAIN
kernel/irq/Kconfig:60:	symbol IRQ_DOMAIN is selected by REGMAP
drivers/base/regmap/Kconfig:6:	symbol REGMAP is selected by MUX_MMIO
drivers/mux/Kconfig:48:	symbol MUX_MMIO depends on MULTIPLEXER
drivers/mux/Kconfig:6:	symbol MULTIPLEXER is selected by MDIO_BUS_MUX_MULTIPLEXER
drivers/net/mdio/Kconfig:275:	symbol MDIO_BUS_MUX_MULTIPLEXER depends on MDIO_DEVICE
drivers/net/mdio/Kconfig:6:	symbol MDIO_DEVICE is selected by PHYLIB
drivers/net/phy/Kconfig:16:	symbol PHYLIB is selected by ARC_EMAC_CORE

after this patch: (5 lines of detail)
drivers/mux/Kconfig:6:error: recursive dependency detected!
drivers/mux/Kconfig:6:	symbol MULTIPLEXER is selected by MDIO_BUS_MUX_MULTIPLEXER
drivers/net/mdio/Kconfig:275:	symbol MDIO_BUS_MUX_MULTIPLEXER depends on MDIO_BUS
drivers/net/mdio/Kconfig:13:	symbol MDIO_BUS is selected by REGMAP
drivers/base/regmap/Kconfig:6:	symbol REGMAP is selected by MUX_MMIO
drivers/mux/Kconfig:48:	symbol MUX_MMIO depends on MULTIPLEXER

[1] https://lore.kernel.org/lkml/20230210115625.GA30942@pengutronix.de/

Fixes: 63c60e3a6dc3 ("of: OF_IRQ should depend on IRQ_DOMAIN")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Rob Herring <robh@kernel.org>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Philipp Zabel <p.zabel@pengutronix.de>
Cc: Peter Rosin <peda@axentia.se>
Cc: devicetree@vger.kernel.org
---
v2: update patch description, rebase & resend

 drivers/of/Kconfig |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff -- a/drivers/of/Kconfig b/drivers/of/Kconfig
--- a/drivers/of/Kconfig
+++ b/drivers/of/Kconfig
@@ -80,7 +80,8 @@ config OF_ADDRESS
 
 config OF_IRQ
 	def_bool y
-	depends on !SPARC && IRQ_DOMAIN
+	depends on !SPARC
+	select IRQ_DOMAIN
 
 config OF_RESERVED_MEM
 	def_bool OF_EARLY_FLATTREE