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([2600:1700:2000:b002:a1d1:dd74:a6de:fdf]) by smtp.gmail.com with ESMTPSA id ul9-20020a05620a6d0900b0077f0d3bac3bsm4896980qkn.76.2023.12.13.17.03.20 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 13 Dec 2023 17:03:21 -0800 (PST) Message-ID: <7ed20fcf-8a9d-40d5-b913-b5d2da443cd6@sifive.com> Date: Wed, 13 Dec 2023 19:03:20 -0600 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH 10/12] drm/amd/display: Use ARCH_HAS_KERNEL_FPU_SUPPORT Content-Language: en-US To: Michael Ellerman References: <20231208055501.2916202-1-samuel.holland@sifive.com> <20231208055501.2916202-11-samuel.holland@sifive.com> <87h6kpdj20.fsf@mail.lhotse> From: Samuel Holland In-Reply-To: <87h6kpdj20.fsf@mail.lhotse> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit 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-arch@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org, amd-gfx@lists.freedesktop.org, Christoph Hellwig , Timothy Pearson , loongarch@lists.linux.dev, linux-riscv@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, linux-arm-kernel@lists.infradead.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On 2023-12-11 6:23 AM, Michael Ellerman wrote: > Hi Samuel, > > Thanks for trying to clean all this up. > > One problem below. > > Samuel Holland writes: >> Now that all previously-supported architectures select >> ARCH_HAS_KERNEL_FPU_SUPPORT, this code can depend on that symbol instead >> of the existing list of architectures. It can also take advantage of the >> common kernel-mode FPU API and method of adjusting CFLAGS. >> >> Signed-off-by: Samuel Holland > ... >> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/dc_fpu.c b/drivers/gpu/drm/amd/display/amdgpu_dm/dc_fpu.c >> index 4ae4720535a5..b64f917174ca 100644 >> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/dc_fpu.c >> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/dc_fpu.c >> @@ -87,20 +78,9 @@ void dc_fpu_begin(const char *function_name, const int line) >> WARN_ON_ONCE(!in_task()); >> preempt_disable(); >> depth = __this_cpu_inc_return(fpu_recursion_depth); >> - >> if (depth == 1) { >> -#if defined(CONFIG_X86) || defined(CONFIG_LOONGARCH) >> + BUG_ON(!kernel_fpu_available()); >> kernel_fpu_begin(); >> -#elif defined(CONFIG_PPC64) >> - if (cpu_has_feature(CPU_FTR_VSX_COMP)) >> - enable_kernel_vsx(); >> - else if (cpu_has_feature(CPU_FTR_ALTIVEC_COMP)) >> - enable_kernel_altivec(); > > Note altivec. > >> - else if (!cpu_has_feature(CPU_FTR_FPU_UNAVAILABLE)) >> - enable_kernel_fp(); >> -#elif defined(CONFIG_ARM64) >> - kernel_neon_begin(); >> -#endif >> } >> >> TRACE_DCN_FPU(true, function_name, line, depth); >> diff --git a/drivers/gpu/drm/amd/display/dc/dml/Makefile b/drivers/gpu/drm/amd/display/dc/dml/Makefile >> index ea7d60f9a9b4..5aad0f572ba3 100644 >> --- a/drivers/gpu/drm/amd/display/dc/dml/Makefile >> +++ b/drivers/gpu/drm/amd/display/dc/dml/Makefile >> @@ -25,40 +25,8 @@ >> # It provides the general basic services required by other DAL >> # subcomponents. >> >> -ifdef CONFIG_X86 >> -dml_ccflags-$(CONFIG_CC_IS_GCC) := -mhard-float >> -dml_ccflags := $(dml_ccflags-y) -msse >> -endif >> - >> -ifdef CONFIG_PPC64 >> -dml_ccflags := -mhard-float -maltivec >> -endif > > And altivec is enabled in the flags there. > > That doesn't match your implementation for powerpc in patch 7, which > only deals with float. > > I suspect the AMD driver actually doesn't need altivec enabled, but I > don't know that for sure. It compiles without it, but I don't have a GPU > to actually test. I've added Timothy on Cc who added the support for > powerpc to the driver originally, hopefully he has a test system. I tested this series on a POWER9 system with an AMD Radeon RX 6400 GPU (which requires this FPU code to initialize), and got functioning graphics output. > Anyway if that's true that it doesn't need altivec we should probably do > a lead-up patch that drops altivec from the AMD driver explicitly, eg. > as below. That makes sense to me. Do you want to provide your Signed-off-by so I can send this patch with your authorship? Regards, Samuel > cheers > > > diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/dc_fpu.c b/drivers/gpu/drm/amd/display/amdgpu_dm/dc_fpu.c > index 4ae4720535a5..0de16796466b 100644 > --- a/drivers/gpu/drm/amd/display/amdgpu_dm/dc_fpu.c > +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/dc_fpu.c > @@ -92,11 +92,7 @@ void dc_fpu_begin(const char *function_name, const int line) > #if defined(CONFIG_X86) || defined(CONFIG_LOONGARCH) > kernel_fpu_begin(); > #elif defined(CONFIG_PPC64) > - if (cpu_has_feature(CPU_FTR_VSX_COMP)) > - enable_kernel_vsx(); > - else if (cpu_has_feature(CPU_FTR_ALTIVEC_COMP)) > - enable_kernel_altivec(); > - else if (!cpu_has_feature(CPU_FTR_FPU_UNAVAILABLE)) > + if (!cpu_has_feature(CPU_FTR_FPU_UNAVAILABLE)) > enable_kernel_fp(); > #elif defined(CONFIG_ARM64) > kernel_neon_begin(); > @@ -125,11 +121,7 @@ void dc_fpu_end(const char *function_name, const int line) > #if defined(CONFIG_X86) || defined(CONFIG_LOONGARCH) > kernel_fpu_end(); > #elif defined(CONFIG_PPC64) > - if (cpu_has_feature(CPU_FTR_VSX_COMP)) > - disable_kernel_vsx(); > - else if (cpu_has_feature(CPU_FTR_ALTIVEC_COMP)) > - disable_kernel_altivec(); > - else if (!cpu_has_feature(CPU_FTR_FPU_UNAVAILABLE)) > + if (!cpu_has_feature(CPU_FTR_FPU_UNAVAILABLE)) > disable_kernel_fp(); > #elif defined(CONFIG_ARM64) > kernel_neon_end(); > diff --git a/drivers/gpu/drm/amd/display/dc/dml/Makefile b/drivers/gpu/drm/amd/display/dc/dml/Makefile > index 6042a5a6a44f..554c39024a40 100644 > --- a/drivers/gpu/drm/amd/display/dc/dml/Makefile > +++ b/drivers/gpu/drm/amd/display/dc/dml/Makefile > @@ -31,7 +31,7 @@ dml_ccflags := $(dml_ccflags-y) -msse > endif > > ifdef CONFIG_PPC64 > -dml_ccflags := -mhard-float -maltivec > +dml_ccflags := -mhard-float > endif > > ifdef CONFIG_ARM64 > diff --git a/drivers/gpu/drm/amd/display/dc/dml2/Makefile b/drivers/gpu/drm/amd/display/dc/dml2/Makefile > index acff3449b8d7..7b51364084b5 100644 > --- a/drivers/gpu/drm/amd/display/dc/dml2/Makefile > +++ b/drivers/gpu/drm/amd/display/dc/dml2/Makefile > @@ -30,7 +30,7 @@ dml2_ccflags := $(dml2_ccflags-y) -msse > endif > > ifdef CONFIG_PPC64 > -dml2_ccflags := -mhard-float -maltivec > +dml2_ccflags := -mhard-float > endif > > ifdef CONFIG_ARM64