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| author | Sebastian Andrzej Siewior <bigeasy@linutronix.de> | 2023-09-21 16:15:13 +0200 |
|---|---|---|
| committer | Alex Deucher <alexander.deucher@amd.com> | 2023-10-05 17:50:50 -0400 |
| commit | de5e73dc6baf4a2969493a2f16aed3fe222eb363 (patch) | |
| tree | a176ea28a474993ffefda660ed9151e9e412b6c7 | |
| parent | 9c77dcf6a5b179a9574b2f9633c6e2cdf52fafec (diff) | |
| download | linux-de5e73dc6baf4a2969493a2f16aed3fe222eb363.tar.gz linux-de5e73dc6baf4a2969493a2f16aed3fe222eb363.tar.bz2 linux-de5e73dc6baf4a2969493a2f16aed3fe222eb363.zip | |
drm/amd/display: Simplify the per-CPU usage.
The fpu_recursion_depth counter is used to ensure that dc_fpu_begin()
can be invoked multiple times while the FPU-disable function itself is
only invoked once. Also the counter part (dc_fpu_end()) is ballanced
properly.
Instead of using the get_cpu_ptr() dance around the inc it is simpler to
increment the per-CPU variable directly. Also the per-CPU variable has
to be incremented and decremented on the same CPU. This is ensured by
the inner-part which disables preemption. This is kind of not obvious,
works and the preempt-counter is touched a few times for no reason.
Disable preemption before incrementing fpu_recursion_depth for the first
time. Keep preemption disabled until dc_fpu_end() where the counter is
decremented making it obvious that the preemption has to stay disabled
while the counter is non-zero.
Use simple inc/dec functions.
Remove the nested preempt_disable/enable functions which are now not
needed.
Acked-by: Harry Wentland <harry.wentland@amd.com>
Reviewed-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Hamza Mahfooz <hamza.mahfooz@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
| -rw-r--r-- | drivers/gpu/drm/amd/display/amdgpu_dm/dc_fpu.c | 50 |
1 files changed, 20 insertions, 30 deletions
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 86f4c0e04654..8bd5926b47e0 100644 --- a/drivers/gpu/drm/amd/display/amdgpu_dm/dc_fpu.c +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/dc_fpu.c @@ -60,11 +60,9 @@ static DEFINE_PER_CPU(int, fpu_recursion_depth); */ inline void dc_assert_fp_enabled(void) { - int *pcpu, depth = 0; + int depth; - pcpu = get_cpu_ptr(&fpu_recursion_depth); - depth = *pcpu; - put_cpu_ptr(&fpu_recursion_depth); + depth = __this_cpu_read(fpu_recursion_depth); ASSERT(depth >= 1); } @@ -84,32 +82,27 @@ inline void dc_assert_fp_enabled(void) */ void dc_fpu_begin(const char *function_name, const int line) { - int *pcpu; + int depth; - pcpu = get_cpu_ptr(&fpu_recursion_depth); - *pcpu += 1; + preempt_disable(); + depth = __this_cpu_inc_return(fpu_recursion_depth); - if (*pcpu == 1) { + if (depth == 1) { #if defined(CONFIG_X86) || defined(CONFIG_LOONGARCH) kernel_fpu_begin(); #elif defined(CONFIG_PPC64) - if (cpu_has_feature(CPU_FTR_VSX_COMP)) { - preempt_disable(); + if (cpu_has_feature(CPU_FTR_VSX_COMP)) enable_kernel_vsx(); - } else if (cpu_has_feature(CPU_FTR_ALTIVEC_COMP)) { - preempt_disable(); + else if (cpu_has_feature(CPU_FTR_ALTIVEC_COMP)) enable_kernel_altivec(); - } else if (!cpu_has_feature(CPU_FTR_FPU_UNAVAILABLE)) { - preempt_disable(); + 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, *pcpu); - put_cpu_ptr(&fpu_recursion_depth); + TRACE_DCN_FPU(true, function_name, line, depth); } /** @@ -124,29 +117,26 @@ void dc_fpu_begin(const char *function_name, const int line) */ void dc_fpu_end(const char *function_name, const int line) { - int *pcpu; + int depth; - pcpu = get_cpu_ptr(&fpu_recursion_depth); - *pcpu -= 1; - if (*pcpu <= 0) { + depth = __this_cpu_dec_return(fpu_recursion_depth); + if (depth == 0) { #if defined(CONFIG_X86) || defined(CONFIG_LOONGARCH) kernel_fpu_end(); #elif defined(CONFIG_PPC64) - if (cpu_has_feature(CPU_FTR_VSX_COMP)) { + if (cpu_has_feature(CPU_FTR_VSX_COMP)) disable_kernel_vsx(); - preempt_enable(); - } else if (cpu_has_feature(CPU_FTR_ALTIVEC_COMP)) { + else if (cpu_has_feature(CPU_FTR_ALTIVEC_COMP)) disable_kernel_altivec(); - preempt_enable(); - } else if (!cpu_has_feature(CPU_FTR_FPU_UNAVAILABLE)) { + else if (!cpu_has_feature(CPU_FTR_FPU_UNAVAILABLE)) disable_kernel_fp(); - preempt_enable(); - } #elif defined(CONFIG_ARM64) kernel_neon_end(); #endif + } else { + WARN_ON_ONCE(depth < 0); } - TRACE_DCN_FPU(false, function_name, line, *pcpu); - put_cpu_ptr(&fpu_recursion_depth); + TRACE_DCN_FPU(false, function_name, line, depth); + preempt_enable(); } |