Hi Christophe, On Tue, Mar 9, 2021 at 9:52 AM Christophe Leroy <christophe.le...@csgroup.eu> wrote: > Le 09/03/2021 à 09:45, Geert Uytterhoeven a écrit : > > On Tue, Mar 9, 2021 at 9:39 AM Christophe Leroy > > <christophe.le...@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: sta...@vger.kernel.org > >> Signed-off-by: Christophe Leroy <christophe.le...@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.
IC. So you might as well have an empty (dummy) function instead? Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- ge...@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds