Re: [PATCH] net: broadcom: Add PTP_1588_CLOCK_OPTIONAL dependency for BCMGENET under ARCH_BCM2835

[Jakub Kicinski <kuba@kernel.org>]

On Fri, 25 Nov 2022 19:50:03 +0800 YueHaibing wrote:
> commit 8d820bc9d12b ("net: broadcom: Fix BCMGENET Kconfig") fixes the build
> that contain 99addbe31f55 ("net: broadcom: Select BROADCOM_PHY for BCMGENET")
> and enable BCMGENET=y but PTP_1588_CLOCK_OPTIONAL=m, which otherwise
> leads to a link failure. However this may trigger a runtime failure.
> 
> Fix the original issue by propagating the PTP_1588_CLOCK_OPTIONAL dependency
> of BROADCOM_PHY down to BCMGENET.
> 
> Fixes: 8d820bc9d12b ("net: broadcom: Fix BCMGENET Kconfig")
> Fixes: 99addbe31f55 ("net: broadcom: Select BROADCOM_PHY for BCMGENET")
> Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
> Suggested-by: Arnd Bergmann <arnd@arndb.de>
> Signed-off-by: YueHaibing <yuehaibing@huawei.com>
> ---
>  drivers/net/ethernet/broadcom/Kconfig | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/broadcom/Kconfig b/drivers/net/ethernet/broadcom/Kconfig
> index 55dfdb34e37b..f4ca0c6c0f51 100644
> --- a/drivers/net/ethernet/broadcom/Kconfig
> +++ b/drivers/net/ethernet/broadcom/Kconfig
> @@ -71,13 +71,14 @@ config BCM63XX_ENET
>  config BCMGENET
>  	tristate "Broadcom GENET internal MAC support"
>  	depends on HAS_IOMEM
> +	depends on PTP_1588_CLOCK_OPTIONAL || !ARCH_BCM2835
>  	select MII
>  	select PHYLIB
>  	select FIXED_PHY
>  	select BCM7XXX_PHY
>  	select MDIO_BCM_UNIMAC
>  	select DIMLIB
> -	select BROADCOM_PHY if (ARCH_BCM2835 && PTP_1588_CLOCK_OPTIONAL)
> +	select BROADCOM_PHY if ARCH_BCM2835
>  	help
>  	  This driver supports the built-in Ethernet MACs found in the
>  	  Broadcom BCM7xxx Set Top Box family chipset.

What's the code path that leads to the failure? I want to double check
that the driver is handling the PTP registration return codes correctly.
IIUC this is a source of misunderstandings in the PTP API.

Richard, here's the original report:
https://lore.kernel.org/all/CA+G9fYvKfbJHcMZtybf_0Ru3+6fKPg9HwWTOhdCLrOBXMaeG1A@mail.gmail.com/