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Wed, 10 Mar 2021 14:33:26 +0100 (CET) Received: from messagerie.si.c-s.fr (messagerie.si.c-s.fr [192.168.25.192]) by pegase1.c-s.fr (Postfix) with ESMTP id 4DwY1d6BkdzB09Zn; Wed, 10 Mar 2021 14:33:25 +0100 (CET) Received: from localhost (localhost [127.0.0.1]) by messagerie.si.c-s.fr (Postfix) with ESMTP id F0FE88B78C; Wed, 10 Mar 2021 14:33:26 +0100 (CET) X-Virus-Scanned: amavisd-new at c-s.fr Received: from messagerie.si.c-s.fr ([127.0.0.1]) by localhost (messagerie.si.c-s.fr [127.0.0.1]) (amavisd-new, port 10023) with ESMTP id tX8OhmiwHzB5; Wed, 10 Mar 2021 14:33:26 +0100 (CET) Received: from [192.168.4.90] (unknown [192.168.4.90]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 1C11A8B77E; Wed, 10 Mar 2021 14:33:26 +0100 (CET) Subject: Re: [PATCH] powerpc: Fix missing declaration of [en/dis]able_kernel_vsx() To: Geert Uytterhoeven References: <8d7d285a027e9d21f5ff7f850fa71a2655b0c4af.1615279170.git.christophe.leroy@csgroup.eu> From: Christophe Leroy Message-ID: <5b579a54-e596-bcf2-b003-5c28345447b7@csgroup.eu> Date: Wed, 10 Mar 2021 14:33:25 +0100 User-Agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: fr Content-Transfer-Encoding: 8bit X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Linux Kernel Mailing List , amd-gfx list , Paul Mackerras , Alex Deucher , linuxppc-dev , =?UTF-8?Q?Christian_K=c3=b6nig?= Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Hi Geert, Le 09/03/2021 à 11:55, Geert Uytterhoeven a écrit : > Hi Christophe, > > On Tue, Mar 9, 2021 at 10:58 AM Christophe Leroy > wrote: >> Le 09/03/2021 à 10:16, Geert Uytterhoeven a écrit : >>> On Tue, Mar 9, 2021 at 9:52 AM Christophe Leroy >>> wrote: >>>> Le 09/03/2021 à 09:45, Geert Uytterhoeven a écrit : >>>>> On Tue, Mar 9, 2021 at 9:39 AM Christophe Leroy >>>>> wrote: >>>>>> Add stub instances of enable_kernel_vsx() and disable_kernel_vsx() >>>>>> when CONFIG_VSX is not set, to avoid following build failure. >>>>>> >>>>>> CC [M] drivers/gpu/drm/amd/amdgpu/../display/dc/calcs/dcn_calcs.o >>>>>> In file included from ./drivers/gpu/drm/amd/amdgpu/../display/dc/dm_services_types.h:29, >>>>>> from ./drivers/gpu/drm/amd/amdgpu/../display/dc/dm_services.h:37, >>>>>> from drivers/gpu/drm/amd/amdgpu/../display/dc/calcs/dcn_calcs.c:27: >>>>>> drivers/gpu/drm/amd/amdgpu/../display/dc/calcs/dcn_calcs.c: In function 'dcn_bw_apply_registry_override': >>>>>> ./drivers/gpu/drm/amd/amdgpu/../display/dc/os_types.h:64:3: error: implicit declaration of function 'enable_kernel_vsx'; did you mean 'enable_kernel_fp'? [-Werror=implicit-function-declaration] >>>>>> 64 | enable_kernel_vsx(); \ >>>>>> | ^~~~~~~~~~~~~~~~~ >>>>>> drivers/gpu/drm/amd/amdgpu/../display/dc/calcs/dcn_calcs.c:640:2: note: in expansion of macro 'DC_FP_START' >>>>>> 640 | DC_FP_START(); >>>>>> | ^~~~~~~~~~~ >>>>>> ./drivers/gpu/drm/amd/amdgpu/../display/dc/os_types.h:75:3: error: implicit declaration of function 'disable_kernel_vsx'; did you mean 'disable_kernel_fp'? [-Werror=implicit-function-declaration] >>>>>> 75 | disable_kernel_vsx(); \ >>>>>> | ^~~~~~~~~~~~~~~~~~ >>>>>> drivers/gpu/drm/amd/amdgpu/../display/dc/calcs/dcn_calcs.c:676:2: note: in expansion of macro 'DC_FP_END' >>>>>> 676 | DC_FP_END(); >>>>>> | ^~~~~~~~~ >>>>>> cc1: some warnings being treated as errors >>>>>> make[5]: *** [drivers/gpu/drm/amd/amdgpu/../display/dc/calcs/dcn_calcs.o] Error 1 >>>>>> >>>>>> Fixes: 16a9dea110a6 ("amdgpu: Enable initial DCN support on POWER") >>>>>> Cc: stable@vger.kernel.org >>>>>> Signed-off-by: Christophe Leroy >>>>> >>>>> Thanks for your patch! >>>>> >>>>>> --- a/arch/powerpc/include/asm/switch_to.h >>>>>> +++ b/arch/powerpc/include/asm/switch_to.h >>>>>> @@ -71,6 +71,16 @@ static inline void disable_kernel_vsx(void) >>>>>> { >>>>>> msr_check_and_clear(MSR_FP|MSR_VEC|MSR_VSX); >>>>>> } >>>>>> +#else >>>>>> +static inline void enable_kernel_vsx(void) >>>>>> +{ >>>>>> + BUILD_BUG(); >>>>>> +} >>>>>> + >>>>>> +static inline void disable_kernel_vsx(void) >>>>>> +{ >>>>>> + BUILD_BUG(); >>>>>> +} >>>>>> #endif >>>>> >>>>> I'm wondering how this is any better than the current situation: using >>>>> BUILD_BUG() will still cause a build failure? >>>> >>>> No it won't cause a failure. In drivers/gpu/drm/amd/display/dc/os_types.h you have: >>>> >>>> #define DC_FP_START() { \ >>>> if (cpu_has_feature(CPU_FTR_VSX_COMP)) { \ >>>> preempt_disable(); \ >>>> enable_kernel_vsx(); \ >>>> } else if (cpu_has_feature(CPU_FTR_ALTIVEC_COMP)) { \ >>>> preempt_disable(); \ >>>> enable_kernel_altivec(); \ >>>> } else if (!cpu_has_feature(CPU_FTR_FPU_UNAVAILABLE)) { \ >>>> preempt_disable(); \ >>>> enable_kernel_fp(); \ >>>> } \ >>>> >>>> When CONFIG_VSX is not selected, cpu_has_feature(CPU_FTR_VSX_COMP) constant folds to 'false' so the >>>> call to enable_kernel_vsx() is discarded and the build succeeds. >>> >>> IC. So you might as well have an empty (dummy) function instead? >>> >> >> But with an empty function, you take the risk that one day, someone calls it without checking that >> CONFIG_VSX is selected. Here if someone does that, build will fail. > > OK, convinced. > Note that following build test performed on kisskb, with gcc 4.9 the following change is required in addition: https://patchwork.ozlabs.org/project/linuxppc-dev/patch/b231dfa040ce4cc37f702f5c3a595fdeabfe0462.1615378209.git.christophe.leroy@csgroup.eu/ Christophe