[PATCH net-next] dsa: sja1105: fix reverse dependency

[Arnd Bergmann]

From: Arnd Bergmann <arnd@xxxxxxxx>

The DSA driver and the tag driver for sja1105 are closely linked,
and recently the dependency started becoming visible in the form
of the sja1110_process_meta_tstamp() that gets exported by one
and used by the other.

This causes a rare build failure with CONFIG_NET_DSA_TAG_SJA1105=y
and CONFIG_NET_DSA_SJA1105=m, as the 'select' statement only
prevents the opposite configuration:

aarch64-linux-ld: net/dsa/tag_sja1105.o: in function `sja1110_rcv':
tag_sja1105.c:(.text.sja1110_rcv+0x164): undefined reference to `sja1110_process_meta_tstamp'

Add a stricter dependency for the CONFIG_NET_DSA_TAG_SJA110y to
prevent it from being built-in when the other one is not.

Fixes: 566b18c8b752 ("net: dsa: sja1105: implement TX timestamping for SJA1110")
Fixes: 227d07a07ef1 ("net: dsa: sja1105: Add support for traffic through standalone ports")
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
---
Not sure if there is a more logical way to deal with this,
but the added dependency does help avoid the build failure.

I found this one while verifying the PTP dependency patch, but
it's really a separate issue.
---
 net/dsa/Kconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/dsa/Kconfig b/net/dsa/Kconfig
index bca1b5d66df2..548285539752 100644
--- a/net/dsa/Kconfig
+++ b/net/dsa/Kconfig
@@ -138,6 +138,7 @@ config NET_DSA_TAG_LAN9303
 
 config NET_DSA_TAG_SJA1105
 	tristate "Tag driver for NXP SJA1105 switches"
+	depends on NET_DSA_SJA1105 || !NET_DSA_SJA1105
 	select PACKING
 	help
 	  Say Y or M if you want to enable support for tagging frames with the
-- 
2.29.2