Re: [net-next PATCH v2 1/2] net: phy: mediatek: permit to compile test GE SOC PHY driver

[Christian Marangi <ansuelsmth@gmail.com>]

On Thu, Apr 10, 2025 at 12:31:05PM +0200, Arnd Bergmann wrote:
> On Thu, Apr 10, 2025, at 12:04, Christian Marangi wrote:
> > When commit 462a3daad679 ("net: phy: mediatek: fix compile-test
> > dependencies") fixed the dependency, it should have also introduced
> > an or on COMPILE_TEST to permit this driver to be compile-tested even if
> > NVMEM_MTK_EFUSE wasn't selected
> 
> Why does this matter? NVMEM_MTK_EFUSE can be enabled for both
> allmodconfig and randconfig builds on any architecture, so you
> get build coverage either way, it's just a little less likely
> to be enabled in randconfig I guess?
>

If we base stuff on the fact that everything is selected or that a
random config by luck selects it, then COMPILE_TEST doesn't make sense
at all.

For my personal test, I wanted to test the driver on a simple x86 build
without having to depend on ARCH or having to cross compile. Won't
happen on real world scenario? Totally. I should be able to compile it?
Yes.

> > diff --git a/drivers/net/phy/mediatek/Kconfig b/drivers/net/phy/mediatek/Kconfig
> > index 2a8ac5aed0f8..6a4c2b328c41 100644
> > --- a/drivers/net/phy/mediatek/Kconfig
> > +++ b/drivers/net/phy/mediatek/Kconfig
> > @@ -15,8 +15,7 @@ config MEDIATEK_GE_PHY
> > 
> >  config MEDIATEK_GE_SOC_PHY
> >  	tristate "MediaTek SoC Ethernet PHYs"
> > -	depends on (ARM64 && ARCH_MEDIATEK) || COMPILE_TEST
> > -	depends on NVMEM_MTK_EFUSE
> > +	depends on (ARM64 && ARCH_MEDIATEK && NVMEM_MTK_EFUSE) || COMPILE_TEST
> >  	select MTK_NET_PHYLIB
> >  	help
> >  	  Supports MediaTek SoC built-in Gigabit Ethernet PHYs.
> > -- 
> 
> I would expect this to break the build with CONFIG_NVMEM=m
> and MEDIATEK_GE_SOC_PHY=y.
> 
> The normal thing here would be to have a dependency on
> CONFIG_NVMEM in place of the NVMEM_MTK_EFUSE dependency,
> or possible on 'NVMEM || !NVMEM' if you want to make it
> more likely to be enabled in randconfig builds.
> 

The big idea of these dependency is that... In MTK the internal PHY of
the switch needs calibration or it won't work hence it doesn't make
sense to select the PHY as it won't ever work without the NVMEM driver.

But from a compile test view where we only evaluate if the driver have
compilation error or other kind of warning, we should not care...

-- 
	Ansuel