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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':
This is a recurring problem in many drivers, and we have discussed
it several times befores, without reaching a consensus. I'm providing
a link to the previous email thread for reference, which discusses
some related problems.
To solve the dependency issue better than the 'imply' keyword, introduce a
separate Kconfig symbol "CONFIG_PTP_1588_CLOCK_OPTIONAL" that any driver
can depend on if it is able to use PTP support when available, but works
fine without it. Whenever CONFIG_PTP_1588_CLOCK=m, those drivers are
then prevented from being built-in, the same way as with a 'depends on
PTP_1588_CLOCK || !PTP_1588_CLOCK' dependency that does the same trick,
but that can be rather confusing when you first see it.
Since this should cover the dependencies correctly, the IS_REACHABLE()
hack in the header is no longer needed now, and can be turned back
into a normal IS_ENABLED() check. Any driver that gets the dependency
wrong will now cause a link time failure rather than being unable to use
PTP support when that is in a loadable module.
However, the two recently added ptp_get_vclocks_index() and
ptp_convert_timestamp() interfaces are only called from builtin code with
ethtool and socket timestamps, so keep the current behavior by stubbing
those out completely when PTP is in a loadable module. This should be
addressed properly in a follow-up.
As Richard suggested, we may want to actually turn PTP support into a
'bool' option later on, preventing it from being a loadable module
altogether, which would be one way to solve the problem with the ethtool
interface.
Fixes: 06c16d89d2 ("ice: register 1588 PTP clock device object for E810 devices")
Link: https://lore.kernel.org/netdev/20210804121318.337276-1-arnd@kernel.org/
Link: https://lore.kernel.org/netdev/CAK8P3a06enZOf=XyZ+zcAwBczv41UuCTz+=0FMf2gBz1_cOnZQ@mail.gmail.com/
Link: https://lore.kernel.org/netdev/CAK8P3a3=eOxE-K25754+fB_-i_0BZzf9a9RfPTX3ppSwu9WZXw@mail.gmail.com/
Link: https://lore.kernel.org/netdev/20210726084540.3282344-1-arnd@kernel.org/
Acked-by: Shannon Nelson <snelson@pensando.io>
Acked-by: Jacob Keller <jacob.e.keller@intel.com>
Acked-by: Richard Cochran <richardcochran@gmail.com>
Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20210812183509.1362782-1-arnd@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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54 lines
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# SPDX-License-Identifier: GPL-2.0-only
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#
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# Cadence device configuration
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#
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config NET_VENDOR_CADENCE
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bool "Cadence devices"
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depends on HAS_IOMEM
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default y
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help
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If you have a network (Ethernet) card belonging to this class, say Y.
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If unsure, say Y.
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Note that the answer to this question doesn't directly affect the
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kernel: saying N will just cause the configurator to skip all the
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remaining Cadence network card questions. If you say Y, you will be
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asked for your specific card in the following questions.
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if NET_VENDOR_CADENCE
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config MACB
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tristate "Cadence MACB/GEM support"
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depends on HAS_DMA && COMMON_CLK
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depends on PTP_1588_CLOCK_OPTIONAL
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select PHYLINK
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select CRC32
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help
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The Cadence MACB ethernet interface is found on many Atmel AT32 and
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AT91 parts. This driver also supports the Cadence GEM (Gigabit
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Ethernet MAC found in some ARM SoC devices). Say Y to include
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support for the MACB/GEM chip.
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To compile this driver as a module, choose M here: the module
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will be macb.
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config MACB_USE_HWSTAMP
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bool "Use IEEE 1588 hwstamp"
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depends on MACB
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depends on PTP_1588_CLOCK
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default y
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help
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Enable IEEE 1588 Precision Time Protocol (PTP) support for MACB.
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config MACB_PCI
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tristate "Cadence PCI MACB/GEM support"
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depends on MACB && PCI
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help
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This is PCI wrapper for MACB driver.
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To compile this driver as a module, choose M here: the module
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will be called macb_pci.
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endif # NET_VENDOR_CADENCE
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