Re: [PATCH v2] net: ethernet: ti: Remove TI_CPTS_MOD workaround

From: Grygorii Strashko
Date: Tue May 05 2020 - 03:42:27 EST




On 04/05/2020 19:57, Clay McClure wrote:
My recent commit b6d49cab44b5 ("net: Make PTP-specific drivers depend on PTP_1588_CLOCK")
exposes a missing dependency in defconfigs that select TI_CPTS without
selecting PTP_1588_CLOCK, leading to linker errors of the form:

drivers/net/ethernet/ti/cpsw.o: in function `cpsw_ndo_stop':
cpsw.c:(.text+0x680): undefined reference to `cpts_unregister'
drivers/net/ethernet/ti/cpsw.o: in function `cpsw_remove':
cpsw.c:(.text+0x81c): undefined reference to `cpts_release'
drivers/net/ethernet/ti/cpsw.o: in function `cpsw_rx_handler':
cpsw.c:(.text+0x1324): undefined reference to `cpts_rx_timestamp'
drivers/net/ethernet/ti/cpsw.o: in function `cpsw_ndo_open':
cpsw.c:(.text+0x15ec): undefined reference to `cpts_register'
drivers/net/ethernet/ti/cpsw.o: in function `cpsw_probe':
cpsw.c:(.text+0x2468): undefined reference to `cpts_release'

That's because TI_CPTS_MOD (which is the symbol gating the _compilation_
of cpts.c) now depends on PTP_1588_CLOCK, and so is not enabled in these
configurations, but TI_CPTS (which is the symbol gating _calls_ to the
cpts functions) _is_ enabled. So we end up compiling calls to functions
that don't exist, resulting in the linker errors.

The reason we have two symbols (TI_CPTS and TI_CPTS_MOD) for the same
driver is due to commit be9ca0d33c85 ("cpsw/netcp: work around reverse
cpts dependency"), which introduced TI_CPTS_MOD because (quoting the
commit message):

The dependency is reversed: cpsw and netcp call into cpts,
but cpts depends on the other two in Kconfig. This can lead
to cpts being a loadable module and its callers built-in:

drivers/net/ethernet/ti/cpsw.o: In function `cpsw_remove':
cpsw.c:(.text.cpsw_remove+0xd0): undefined reference to `cpts_release'
drivers/net/ethernet/ti/cpsw.o: In function `cpsw_rx_handler':
cpsw.c:(.text.cpsw_rx_handler+0x2dc): undefined reference to `cpts_rx_timestamp'
drivers/net/ethernet/ti/cpsw.o: In function `cpsw_tx_handler':
cpsw.c:(.text.cpsw_tx_handler+0x7c): undefined reference to `cpts_tx_timestamp'
drivers/net/ethernet/ti/cpsw.o: In function `cpsw_ndo_stop':

Both forms of linker error -- those caused by defconfigs that select
TI_CPTS without PTP_1588_CLOCK and those caused by configuring TI_CPSW
as a built-in and TI_CPTS as a module -- can be avoided by using the
IS_REACHABLE() macro to gate calls to cpts functions, and using the
TI_CPTS symbol to gate compilation of cpts.c. cpts.h already provides
the no-op stub implementations of the cpts functions required to make
this work, we just need to change the existing IS_ENABLED(TI_CPTS)
guards to IS_REACHABLE(TI_CPTS).

With this change there is no longer any need for the TI_CPTS_MOD symbol,
so we can remove it.

To preserve the existing behavior of defconfigs that select TI_CPTS, we
must also select PTP_1588_CLOCK so that the dependency is satisfied.

Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Grygorii Strashko <grygorii.strashko@xxxxxx>
Fixes: b6d49cab44b5 ("net: Make PTP-specific drivers depend on PTP_1588_CLOCK")

It's better if you send v2 not as reply to v1.

just to clarify. After these two patches
- the PTP_1588_CLOCK can still be set to "M"
- which will cause TI_CPTS to be "M",
- but TI_CPSW will still be "Y".

and all above will build and produce built-in CPSW without CPTS support
and cpts.ko which is loadable, but not functional.

Sorry, I'm a little bit lost regarding the target you'are trying to achieve.
At least previously "imply PTP_1588_CLOCK" allowed to select properly PTP_1588_CLOCK
without modifying every defconfig.

Reported-by: kbuild test robot <lkp@xxxxxxxxx>
Signed-off-by: Clay McClure <clay@xxxxxxxxxxx>
---
Changes in v2:

- Don't regenerate the defconfigs, just add PTP_1588_CLOCK.

arch/arm/configs/keystone_defconfig | 1 +
arch/arm/configs/omap2plus_defconfig | 1 +
drivers/net/ethernet/ti/Kconfig | 13 ++++---------
drivers/net/ethernet/ti/Makefile | 2 +-
drivers/net/ethernet/ti/cpsw_ethtool.c | 2 +-
drivers/net/ethernet/ti/cpts.h | 3 +--
drivers/net/ethernet/ti/netcp_ethss.c | 10 +++++-----
7 files changed, 14 insertions(+), 18 deletions(-)

diff --git a/arch/arm/configs/keystone_defconfig b/arch/arm/configs/keystone_defconfig
index 11e2211f9007..84a3b055f253 100644
--- a/arch/arm/configs/keystone_defconfig
+++ b/arch/arm/configs/keystone_defconfig
@@ -147,6 +147,7 @@ CONFIG_I2C_DAVINCI=y
CONFIG_SPI=y
CONFIG_SPI_DAVINCI=y
CONFIG_SPI_SPIDEV=y
+CONFIG_PTP_1588_CLOCK=y
CONFIG_PINCTRL_SINGLE=y
CONFIG_GPIOLIB=y
CONFIG_GPIO_SYSFS=y
diff --git a/arch/arm/configs/omap2plus_defconfig b/arch/arm/configs/omap2plus_defconfig
index 3cc3ca5fa027..8b83d4a5d309 100644
--- a/arch/arm/configs/omap2plus_defconfig
+++ b/arch/arm/configs/omap2plus_defconfig
@@ -274,6 +274,7 @@ CONFIG_SPI_TI_QSPI=m
CONFIG_HSI=m
CONFIG_OMAP_SSI=m
CONFIG_SSI_PROTOCOL=m
+CONFIG_PTP_1588_CLOCK=y
CONFIG_PINCTRL_SINGLE=y
CONFIG_DEBUG_GPIO=y
CONFIG_GPIO_SYSFS=y
diff --git a/drivers/net/ethernet/ti/Kconfig b/drivers/net/ethernet/ti/Kconfig
index 8e348780efb6..f3f8bb724294 100644
--- a/drivers/net/ethernet/ti/Kconfig
+++ b/drivers/net/ethernet/ti/Kconfig
@@ -77,23 +77,18 @@ config TI_CPSW_SWITCHDEV
will be called cpsw_new.
config TI_CPTS
- bool "TI Common Platform Time Sync (CPTS) Support"
+ tristate "TI Common Platform Time Sync (CPTS) Support"
depends on TI_CPSW || TI_KEYSTONE_NETCP || TI_CPSW_SWITCHDEV || COMPILE_TEST
depends on COMMON_CLK
- depends on POSIX_TIMERS
+ depends on PTP_1588_CLOCK

+ default y if TI_CPSW=y || TI_KEYSTONE_NETCP=y || TI_CPSW_SWITCHDEV=y

even with above statement it's possible to force TI_CPTS="M" while CPSW/NETCP="Y"

+ default m

I could be mistaken by above 2 lines seems can be 'imply TI_CPTS'
in TI_CPSW, TI_KEYSTONE_NETCP, TI_CPSW_SWITCHDEV

---help---
This driver supports the Common Platform Time Sync unit of
the CPSW Ethernet Switch and Keystone 2 1g/10g Switch Subsystem.
The unit can time stamp PTP UDP/IPv4 and Layer 2 packets, and the
driver offers a PTP Hardware Clock.
-config TI_CPTS_MOD
- tristate
- depends on TI_CPTS
- depends on PTP_1588_CLOCK
- default y if TI_CPSW=y || TI_KEYSTONE_NETCP=y || TI_CPSW_SWITCHDEV=y
- default m

and this prevented user from forcing TI_CPTS="M" while CPSW/NETCP="Y"

-
config TI_K3_AM65_CPSW_NUSS
tristate "TI K3 AM654x/J721E CPSW Ethernet driver"
depends on ARCH_K3 && OF && TI_K3_UDMA_GLUE_LAYER
diff --git a/drivers/net/ethernet/ti/Makefile b/drivers/net/ethernet/ti/Makefile
index 53792190e9c2..cb26a9d21869 100644

Below small diff should fix build fail:
diff --git a/drivers/net/ethernet/ti/Kconfig b/drivers/net/ethernet/ti/Kconfig
index 8e348780efb6..eeaee47598aa 100644
--- a/drivers/net/ethernet/ti/Kconfig
+++ b/drivers/net/ethernet/ti/Kconfig
@@ -81,6 +81,7 @@ config TI_CPTS
depends on TI_CPSW || TI_KEYSTONE_NETCP || TI_CPSW_SWITCHDEV || COMPILE_TEST
depends on COMMON_CLK
depends on POSIX_TIMERS
+ depends on PTP_1588_CLOCK
---help---
This driver supports the Common Platform Time Sync unit of
the CPSW Ethernet Switch and Keystone 2 1g/10g Switch Subsystem.
@@ -90,7 +91,6 @@ config TI_CPTS
config TI_CPTS_MOD
tristate
depends on TI_CPTS
- depends on PTP_1588_CLOCK
default y if TI_CPSW=y || TI_KEYSTONE_NETCP=y || TI_CPSW_SWITCHDEV=y
default m

Then separate patch can be used to enable PTP_1588_CLOCK in defconfigs.

My personal opinion - it might be better to revert TI CPTS part from
b6d49cab44b5 ("net: Make PTP-specific drivers depend on PTP_1588_CLOCK")
at all.

--
Best regards,
grygorii