Messages in this thread | | | Subject | Re: [PATCH] powerpc: Fix missing declaration of [en/dis]able_kernel_vsx() | From | Christophe Leroy <> | Date | Tue, 9 Mar 2021 09:52:11 +0100 |
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Le 09/03/2021 à 09:45, Geert Uytterhoeven a écrit : > Hi Christophe, > > On Tue, Mar 9, 2021 at 9:39 AM Christophe Leroy > <christophe.leroy@csgroup.eu> 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 <christophe.leroy@csgroup.eu> > > 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.
> > What about adding "depends on !POWERPC || VSX" instead, to prevent > the issue from happening in the first place?
CONFIG_VSX is not required as pointed by the DC_FP_START() macro above and the matching DC_FP_END() macro.
> > Gr{oetje,eeting}s, > > Geert >
Christophe
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