RE: [Intel-wired-lan] [PATCH] ethernet/intel: fix PTP_1588_CLOCK dependencies

-----Original Message-----
From: Intel-wired-lan <redacted> On Behalf Of
Arnd Bergmann
Sent: Monday, July 26, 2021 2:15 PM
To: Brandeburg, Jesse <redacted>; Nguyen, Anthony L
[off-list ref]; David S. Miller [off-list ref];
Jakub Kicinski [off-list ref]; Keller, Jacob E
[off-list ref]
Cc: Arnd Bergmann <arnd@arndb.de>; netdev@vger.kernel.org; Kurt
Kanzenbach [off-list ref]; linux-kernel@vger.kernel.org; intel-
wired-lan@lists.osuosl.org; Saleem, Shiraz [off-list ref]
Subject: [Intel-wired-lan] [PATCH] ethernet/intel: fix PTP_1588_CLOCK
dependencies

From: Arnd Bergmann <arnd@arndb.de>

The 'imply' keyword does not do what most people think it does, it only
politely asks Kconfig to turn on another symbol, but does not prevent it from
being disabled manually or built as a loadable module when the user is built-
in. In the ICE driver, the latter now causes a link failure:

aarch64-linux-ld: drivers/net/ethernet/intel/ice/ice_main.o: in function
`ice_eth_ioctl':
ice_main.c:(.text+0x13b0): undefined reference to `ice_ptp_get_ts_config'
ice_main.c:(.text+0x13b0): relocation truncated to fit: R_AARCH64_CALL26
against undefined symbol `ice_ptp_get_ts_config'
aarch64-linux-ld: ice_main.c:(.text+0x13bc): undefined reference to
`ice_ptp_set_ts_config'
ice_main.c:(.text+0x13bc): relocation truncated to fit: R_AARCH64_CALL26
against undefined symbol `ice_ptp_set_ts_config'
aarch64-linux-ld: drivers/net/ethernet/intel/ice/ice_main.o: in function
`ice_prepare_for_reset':
ice_main.c:(.text+0x31fc): undefined reference to `ice_ptp_release'
ice_main.c:(.text+0x31fc): relocation truncated to fit: R_AARCH64_CALL26
against undefined symbol `ice_ptp_release'
aarch64-linux-ld: drivers/net/ethernet/intel/ice/ice_main.o: in function
`ice_rebuild':

For the other Intel network drivers, there is no link error when the drivers
are built-in and PTP is a loadable module, because linux/ptp_clock_kernel.h
contains an IS_REACHABLE() check, but this just changes the compile-time
failure to a runtime failure, which is arguably worse.

Change all the Intel drivers to use the 'depends on PTP_1588_CLOCK ||
!PTP_1588_CLOCK' trick to prevent the broken configuration, as we already
do for several other drivers. To avoid circular dependencies, this also requires
changing the IGB driver back to using the normal 'depends on I2C' instead of
'select I2C'.

Fixes: 06c16d89d2cb ("ice: register 1588 PTP clock device object for E810
devices")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 drivers/net/ethernet/intel/Kconfig | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

Tested-by: Gurucharan  G <redacted> (A Contingent Worker at Intel)