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drm/amd/display: Add control mechanism for FPU utilization

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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:
- Rebase

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>
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>
This commit is contained in:
Rodrigo Siqueira
2021-07-26 20:52:47 -04:00
committed by Alex Deucher
parent 96ee63730f
commit 2d8471dc37
3 changed files with 63 additions and 31 deletions
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77
drivers/gpu/drm/amd/display/amdgpu_dm/dc_fpu.c
View File

@@ -33,6 +33,19 @@
#include <asm/cputable.h>
#endif
/**
* DOC: DC FPU manipulation overview
*
* DC core uses FPU operations in multiple parts of the code, which requires a
* more specialized way to manage these areas' entrance. To fulfill this
* requirement, we created some wrapper functions that encapsulate
* kernel_fpu_begin/end to better fit our need in the display component. In
* summary, in this file, you can find functions related to FPU operation
* management.
*/
static DEFINE_PER_CPU(int, fpu_recursion_depth);
/**
* dc_fpu_begin - Enables FPU protection
* @function_name: A string containing the function name for debug purposes
@@ -48,22 +61,30 @@
*/
void dc_fpu_begin(const char *function_name, const int line)
{
TRACE_DCN_FPU(true, function_name, line);
int *pcpu;
pcpu = get_cpu_ptr(&fpu_recursion_depth);
*pcpu += 1;
if (*pcpu == 1) {
#if defined(CONFIG_X86)
kernel_fpu_begin();
kernel_fpu_begin();
#elif defined(CONFIG_PPC64)
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();
}
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();
}
#endif
}
TRACE_DCN_FPU(true, function_name, line, *pcpu);
put_cpu_ptr(&fpu_recursion_depth);
}
/**
@@ -78,19 +99,27 @@ void dc_fpu_begin(const char *function_name, const int line)
*/
void dc_fpu_end(const char *function_name, const int line)
{
TRACE_DCN_FPU(false, function_name, line);
int *pcpu;
pcpu = get_cpu_ptr(&fpu_recursion_depth);
*pcpu -= 1;
if (*pcpu <= 0) {
#if defined(CONFIG_X86)
kernel_fpu_end();
kernel_fpu_end();
#elif defined(CONFIG_PPC64)
if (cpu_has_feature(CPU_FTR_VSX_COMP)) {
disable_kernel_vsx();
preempt_enable();
} else if (cpu_has_feature(CPU_FTR_ALTIVEC_COMP)) {
disable_kernel_altivec();
preempt_enable();
} else if (!cpu_has_feature(CPU_FTR_FPU_UNAVAILABLE)) {
disable_kernel_fp();
preempt_enable();
}
if (cpu_has_feature(CPU_FTR_VSX_COMP)) {
disable_kernel_vsx();
preempt_enable();
} else if (cpu_has_feature(CPU_FTR_ALTIVEC_COMP)) {
disable_kernel_altivec();
preempt_enable();
} else if (!cpu_has_feature(CPU_FTR_FPU_UNAVAILABLE)) {
disable_kernel_fp();
preempt_enable();
}
#endif
}
TRACE_DCN_FPU(false, function_name, line, *pcpu);
put_cpu_ptr(&fpu_recursion_depth);
}