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path: root/drivers/gpu/drm/amd/display/amdgpu_dm/dc_fpu.h
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2025-12-08drm/amd/display: Permit DC_FP_START/END only in non-FP compilation unitsArd Biesheuvel
[WHAT] Test the existing CPP macro _LINUX_FPU_COMPILATION_UNIT, which is set when building source files that are permitted to use floating point, in the implementation of DC_FP_START/END so that those are only usable in non-FP code. This is a requirement of the generic kernel mode FPU API, as some architectures (i.e., arm64) cannot safely enable FP codegen in arbitrary code. Cc: Austin Zheng <austin.zheng@amd.com> Cc: Jun Lei <jun.lei@amd.com> Cc: Harry Wentland <harry.wentland@amd.com> Cc: Leo Li <sunpeng.li@amd.com> Cc: Rodrigo Siqueira <siqueira@igalia.com> Cc: Alex Deucher <alexander.deucher@amd.com> Cc: "Christian König" <christian.koenig@amd.com> Cc: amd-gfx@lists.freedesktop.org Cc: dri-devel@lists.freedesktop.org Suggested-by: Christian König <christian.koenig@amd.com> Acked-by: Christian König <christian.koenig@amd.com> Reviewed-by: Alex Hung <alex.hung@amd.com> Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Signed-off-by: Alex Hung <alex.hung@amd.com> Tested-by: Dan Wheeler <daniel.wheeler@amd.com> Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
2021-08-05drm/amd/display: Add DC_FP helper to check FPU stateRodrigo Siqueira
To fully isolate FPU operations in a single place, we must avoid situations where compilers spill FP values to registers due to FP enable in a specific C file. Note that even if we isolate all FPU functions in a single file and call its interface from other files, the compiler might enable the use of FPU before we call DC_FP_START. Nevertheless, it is the programmer's responsibility to invoke DC_FP_START/END in the correct place. To highlight situations where developers forgot to use the FP protection before calling the DC FPU interface functions, we introduce a helper that checks if the function is invoked under FP protection. If not, it will trigger a kernel warning. Changes cince V3: - Rebase Changes cince V2 (Christian): - Do not use this_cpu_* between get/put_cpu_ptr(). - In the kernel documentation, better describe restrictions. - Make dc_assert_fp_enabled trigger the ASSERT message. Changes since V1: - Remove fp_enable variables - Rename dc_is_fp_enabled to dc_assert_fp_enabled - Replace wrong variable type Cc: Harry Wentland <harry.wentland@amd.com> Cc: Anson Jacob <Anson.Jacob@amd.com> Cc: Christian König <christian.koenig@amd.com> Cc: Hersen Wu <hersenxs.wu@amd.com> Cc: Aric Cyr <aric.cyr@amd.com> Cc: Jun Lei <jun.lei@amd.com> Cc: Dmytro Laktyushkin <dmytro.laktyushkin@amd.com> Cc: Qingqing Zhuo <qingqing.zhuo@amd.com> Reported-by: kernel test robot <lkp@intel.com> Signed-off-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com> Reviewed-by: Christian König <christian.koenig@amd.com> Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
2021-08-05drm/amd/display: Add control mechanism for FPURodrigo Siqueira
DC invokes DC_FPU_START/END in multiple parts of the code; this can create a situation where we invoke this FPU operation in a nested way or exit too early. For avoiding this situation, this commit adds a mechanism where dc_fpu_begin/end manages the access to kernel_fpu_begin/end. Change since V3: - Christian: Move PPC64 code to dc_fpu_begin/end. Change since V2: - Christian: Do not use this_cpu_* between get/put_cpu_ptr(). Change since V1: - Use a better variable names - Use get_cpu_ptr and put_cpu_ptr to better balance preemption enable and disable Cc: Harry Wentland <harry.wentland@amd.com> Cc: Anson Jacob <Anson.Jacob@amd.com> Cc: Christian König <christian.koenig@amd.com> Cc: Hersen Wu <hersenxs.wu@amd.com> Cc: Aric Cyr <aric.cyr@amd.com> Cc: Jun Lei <jun.lei@amd.com> Cc: Dmytro Laktyushkin <dmytro.laktyushkin@amd.com> Cc: Qingqing Zhuo <qingqing.zhuo@amd.com> Signed-off-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com> Reviewed-by: Christian König <christian.koenig@amd.com> Signed-off-by: Alex Deucher <alexander.deucher@amd.com>