[PATCH v4 3/4] drm/amd/display: Add control mechanism for FPU utilization
Christian König
christian.koenig at amd.com
Tue Jul 27 07:00:10 UTC 2021
Am 27.07.21 um 02:52 schrieb Rodrigo 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:
> - 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 at amd.com>
> Cc: Anson Jacob <Anson.Jacob at amd.com>
> Cc: Christian König <christian.koenig at amd.com>
> Cc: Hersen Wu <hersenxs.wu at amd.com>
> Cc: Aric Cyr <aric.cyr at amd.com>
> Cc: Jun Lei <jun.lei at amd.com>
> Cc: Dmytro Laktyushkin <dmytro.laktyushkin at amd.com>
> Cc: Qingqing Zhuo <qingqing.zhuo at amd.com>
> Reported-by: kernel test robot <lkp at intel.com>
> Signed-off-by: Rodrigo Siqueira <Rodrigo.Siqueira at amd.com>
Reviewed-by: Christian König <christian.koenig at amd.com>
> ---
> .../amd/display/amdgpu_dm/amdgpu_dm_trace.h | 13 ++--
> .../gpu/drm/amd/display/amdgpu_dm/dc_fpu.c | 77 +++++++++++++------
> drivers/gpu/drm/amd/display/dc/dc_trace.h | 4 +-
> 3 files changed, 63 insertions(+), 31 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_trace.h b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_trace.h
> index 230bb12c405e..fdcaea22b456 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_trace.h
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_trace.h
> @@ -638,23 +638,26 @@ TRACE_EVENT(amdgpu_refresh_rate_track,
> );
>
> TRACE_EVENT(dcn_fpu,
> - TP_PROTO(bool begin, const char *function, const int line),
> - TP_ARGS(begin, function, line),
> + TP_PROTO(bool begin, const char *function, const int line, const int recursion_depth),
> + TP_ARGS(begin, function, line, recursion_depth),
>
> TP_STRUCT__entry(
> __field(bool, begin)
> __field(const char *, function)
> __field(int, line)
> + __field(int, recursion_depth)
> ),
> TP_fast_assign(
> __entry->begin = begin;
> __entry->function = function;
> __entry->line = line;
> + __entry->recursion_depth = recursion_depth;
> ),
> - TP_printk("%s()+%d: %s",
> + TP_printk("%s: recursion_depth: %d: %s()+%d:",
> + __entry->begin ? "begin" : "end",
> + __entry->recursion_depth,
> __entry->function,
> - __entry->line,
> - __entry->begin ? "begin" : "end"
> + __entry->line
> )
> );
>
> 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 d4ab27bf8d04..33807d746e76 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/dc_fpu.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/dc_fpu.c
> @@ -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);
> }
> diff --git a/drivers/gpu/drm/amd/display/dc/dc_trace.h b/drivers/gpu/drm/amd/display/dc/dc_trace.h
> index d598ba697e45..c711797e5c9e 100644
> --- a/drivers/gpu/drm/amd/display/dc/dc_trace.h
> +++ b/drivers/gpu/drm/amd/display/dc/dc_trace.h
> @@ -38,5 +38,5 @@
> #define TRACE_DCN_CLOCK_STATE(dcn_clocks) \
> trace_amdgpu_dm_dc_clocks_state(dcn_clocks)
>
> -#define TRACE_DCN_FPU(begin, function, line) \
> - trace_dcn_fpu(begin, function, line)
> +#define TRACE_DCN_FPU(begin, function, line, ref_count) \
> + trace_dcn_fpu(begin, function, line, ref_count)
More information about the amd-gfx
mailing list