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

[Grygorii Strashko <grygorii.strashko@ti.com>]

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@arndb.de>
> Cc: Grygorii Strashko <grygorii.strashko@ti.com>
> 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@intel.com>
> Signed-off-by: Clay McClure <clay@daemons.net>
> ---
> 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