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Date:   Wed, 5 Apr 2023 16:41:13 +0530
From:   Sunil V L <sunilvl@ventanamicro.com>
To:     Maximilian Luz <luzmaximilian@gmail.com>
Cc:     linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-riscv@lists.infradead.org, linux-acpi@vger.kernel.org,
        linux-crypto@vger.kernel.org, platform-driver-x86@vger.kernel.org,
        llvm@lists.linux.dev, Jonathan Corbet <corbet@lwn.net>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Albert Ou <aou@eecs.berkeley.edu>, Len Brown <lenb@kernel.org>,
        Daniel Lezcano <daniel.lezcano@linaro.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Weili Qian <qianweili@huawei.com>,
        Zhou Wang <wangzhou1@hisilicon.com>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        Marc Zyngier <maz@kernel.org>,
        Hans de Goede <hdegoede@redhat.com>,
        Mark Gross <markgross@kernel.org>,
        Nathan Chancellor <nathan@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Tom Rix <trix@redhat.com>,
        "Rafael J . Wysocki" <rafael@kernel.org>,
        "David S . Miller" <davem@davemloft.net>
Subject: Re: [PATCH V4 22/23] platform/surface: Disable for RISC-V
Message-ID: <ZC1XUdD3DFnNauQ2@sunil-laptop>
References: <20230404182037.863533-1-sunilvl@ventanamicro.com>
 <20230404182037.863533-23-sunilvl@ventanamicro.com>
 <0c433e15-640e-280f-fcb0-a8fe081d1bcc@gmail.com>
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On Wed, Apr 05, 2023 at 11:33:00AM +0200, Maximilian Luz wrote:
> On 4/4/23 20:20, Sunil V L wrote:
> > With CONFIG_ACPI enabled for RISC-V, this driver gets enabled
> > in allmodconfig build. However, RISC-V doesn't support sub-word
> > atomics which is used by this driver. Due to this, the build fails
> > with below error.
> > 
> > In function â€˜ssh_seq_nextâ€™,
> >      inlined from â€˜ssam_request_write_dataâ€™ at drivers/platform/surface/aggregator/controller.c:1483:8:
> > ././include/linux/compiler_types.h:399:45: error: call to â€˜__compiletime_assert_335â€™ declared with attribute error: BUILD_BUG failed
> >    399 |         _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
> >        |                                             ^
> > ./include/linux/compiler.h:78:45: note: in definition of macro â€˜unlikelyâ€™
> >     78 | # define unlikely(x)    __builtin_expect(!!(x), 0)
> >        |                                             ^
> > ././include/linux/compiler_types.h:387:9: note: in expansion of macro â€˜__compiletime_assertâ€™
> >    387 |         __compiletime_assert(condition, msg, prefix, suffix)
> >        |         ^~~~~~~~~~~~~~~~~~~~
> > ././include/linux/compiler_types.h:399:9: note: in expansion of macro â€˜_compiletime_assertâ€™
> >    399 |         _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
> >        |         ^~~~~~~~~~~~~~~~~~~
> > ./include/linux/build_bug.h:39:37: note: in expansion of macro â€˜compiletime_assertâ€™
> >     39 | #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg)
> >        |                                     ^~~~~~~~~~~~~~~~~~
> > ./include/linux/build_bug.h:59:21: note: in expansion of macro â€˜BUILD_BUG_ON_MSGâ€™
> >     59 | #define BUILD_BUG() BUILD_BUG_ON_MSG(1, "BUILD_BUG failed")
> >        |                     ^~~~~~~~~~~~~~~~
> > ./arch/riscv/include/asm/cmpxchg.h:335:17: note: in expansion of macro â€˜BUILD_BUGâ€™
> >    335 |                 BUILD_BUG();                                            \
> >        |                 ^~~~~~~~~
> > ./arch/riscv/include/asm/cmpxchg.h:344:30: note: in expansion of macro â€˜__cmpxchgâ€™
> >    344 |         (__typeof__(*(ptr))) __cmpxchg((ptr),                           \
> >        |                              ^~~~~~~~~
> > ./include/linux/atomic/atomic-instrumented.h:1916:9: note: in expansion of macro â€˜arch_cmpxchgâ€™
> >   1916 |         arch_cmpxchg(__ai_ptr, __VA_ARGS__); \
> >        |         ^~~~~~~~~~~~
> > drivers/platform/surface/aggregator/controller.c:61:32: note: in expansion of macro â€˜cmpxchgâ€™
> >     61 |         while (unlikely((ret = cmpxchg(&c->value, old, new)) != old)) {
> >        |                                ^~~~~~~
> > 
> > So, disable this driver for RISC-V even when ACPI is enabled for now.
> 
> CONFIG_SURFACE_PLATFORMS should be enabled for ARM64 || X86 || COMPILE_TEST only,
> so I guess the issue only happens when compiling with the latter enabled?
> 
> I'm not aware of any current plans of MS to release RISC-V-based Surface
> devices, so you could maybe also just explicitly disable CONFIG_SURFACE_PLATFORMS.
> In any case, I don't see any issues with disabling the whole platform/surface
> or only individual drivers for RISC-V, so for either solution:
> 
> Acked-by: Maximilian Luz <luzmaximilian@gmail.com>
> 
Hi Maximilian,

Thanks!. Yes, COMPILE_TEST gets enabled for allmodconfig builds. Since
the whole intention of COMPILE_TEST appears to be able to compile-test
drivers on a platform than they are supposed to be used, I think it is
better not to skip whole set of drivers but only that which can not build.
So, I prefer to keep this change as is.

Thanks,
Sunil