linux-kernel - Re: [PATCH next] phy: google: fix build dependency for Google Tensor USB PHY

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Message-ID: <CA+zupgztBHTJwNPEOfXjdw9TpcpiVGO=hdFBYk3PUo-0Vf95mg@mail.gmail.com>
Date: Mon, 26 Jan 2026 18:34:11 -0800
From: Roy Luo <royluo@...gle.com>
To: André Draszik <andre.draszik@...aro.org>
Cc: Vinod Koul <vkoul@...nel.org>, Neil Armstrong <neil.armstrong@...aro.org>, 
	Peter Griffin <peter.griffin@...aro.org>, Tudor Ambarus <tudor.ambarus@...aro.org>, 
	Joy Chakraborty <joychakr@...gle.com>, Naveen Kumar <mnkumar@...gle.com>, linux-phy@...ts.infradead.org, 
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, 
	linux-samsung-soc@...r.kernel.org, kernel test robot <lkp@...el.com>
Subject: Re: [PATCH next] phy: google: fix build dependency for Google Tensor
 USB PHY

On Fri, Jan 23, 2026 at 10:52 PM André Draszik <andre.draszik@...aro.org> wrote:
>
> Hi Roy,
>
> On Fri, 2026-01-23 at 15:51 -0800, Roy Luo wrote:
> > On Thu, Jan 22, 2026 at 10:28 PM André Draszik <andre.draszik@...aro.org> wrote:
> > >
> > >
> > > COMPILE_TEST is not limited to ARCH_xxx. It allows drivers to be
> > > compile tested even if the current build doesn't enable whatever
> > > option (like TYPEC).
> > >
> > > See also https://www.kernel.org/doc/html/latest/kbuild/kconfig-language.html#compile-testing
> >
> > "If a config symbol has a dependency, but the code controlled by the
> > config symbol can still be compiled if the dependency is not met",
> > TYPEC doesn't fall into this category as it's mandatory for compiling
> > PHY_GOOGLE_USB.
> > With "depends on TYPEC || COMPILE_TEST", this very build error
> > would resurface when TYPEC=n, COMPILE_TEST=y and
> > PHY_GOOGLE_USB=y. Please let me know if I missed anything.
>
> No it wouldn't. If you look at the build log & .config from the reported
> failure, the error was because:
>
> CONFIG_PHY_GOOGLE_USB=y
> CONFIG_TYPEC=m

You're right about the cause of the build error and sorry I gave
the wrong example. Let's look at this build error scenario with
"depends on TYPEC || COMPILE_TEST":
Given COMPILE_TEST=y and CONFIG_TYPEC=m, the
"depends on" would be evaluated as max(y,m) = y.
Hence, CONFIG_PHY_GOOGLE_USB is allowed to be
set to y, m or n. When it's set to y, the exact build error
would be introduced. I also tested this locally and saw
the build error.

Thanks,
Roy

>
> built-in code can not link against code from a module.
>
> The typec APIs are all stubbed out when TYPEC=n.
>
> Cheers,
> Andre'
>
>
>
> >
> > Thanks,
> > Roy
> >
> > >
> > > Cheers,
> > > Andre'
> > >
> > >
> > > >
> > > > [1] https://lore.kernel.org/all/CA+zupgwgfKwPYqj8G2tNf4pEXNEWA+vL2WYJPhJ16xExgko7Dw@mail.gmail.com/
> > > >
> > > > Regards,
> > > > Roy