| Message ID | 20210331122502.1031073-4-Rodrigo.Siqueira@amd.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | drm/amd/display: Base changes for isolating FPU operation in a single place | expand |
Am 31.03.21 um 14:25 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. > For avoiding this situation, this commit adds a mechanism where > dc_fpu_begin/end manages the access to kernel_fpu_begin/end. In general please name this "recursion" control instead of "ref count". Let's call the child by it's name :) > > Signed-off-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com> > Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com> > --- > .../amd/display/amdgpu_dm/amdgpu_dm_trace.h | 13 ++++--- > .../gpu/drm/amd/display/amdgpu_dm/dc_fpu.c | 34 ++++++++++++++++--- > drivers/gpu/drm/amd/display/dc/dc_trace.h | 4 +-- > 3 files changed, 40 insertions(+), 11 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..cd4f0d3f37fb 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 ref_count), > + TP_ARGS(begin, function, line, ref_count), > > TP_STRUCT__entry( > __field(bool, begin) > __field(const char *, function) > __field(int, line) > + __field(int, ref_count) > ), > TP_fast_assign( > __entry->begin = begin; > __entry->function = function; > __entry->line = line; > + __entry->ref_count = ref_count; > ), > - TP_printk("%s()+%d: %s", > + TP_printk("%s: ref_count: %d: %s()+%d:", > + __entry->begin ? "begin" : "end", > + __entry->ref_count, > __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 ff34007509de..5dcefe193523 100644 > --- a/drivers/gpu/drm/amd/display/amdgpu_dm/dc_fpu.c > +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/dc_fpu.c > @@ -28,6 +28,19 @@ > > #include <asm/fpu/api.h> > > +/** > + * DOC: 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(atomic_t, fpu_ref); > + > /** > * dc_fpu_begin - Enables FPU protection > * @function_name: A string containing the function name for debug purposes > @@ -40,8 +53,14 @@ > */ > void dc_fpu_begin(const char *function_name, const int line) > { > - TRACE_DCN_FPU(true, function_name, line); > - kernel_fpu_begin(); > + int ret; > + atomic_t *local_fpu_ref = this_cpu_ptr(&fpu_ref); > + > + ret = atomic_inc_return(local_fpu_ref); You need to disable preemption for this or otherwise it can be that you schedule to another process. Regards, Christian. > + TRACE_DCN_FPU(true, function_name, line, ret); > + > + if (ret == 1) > + kernel_fpu_begin(); > } > > /** > @@ -56,6 +75,13 @@ 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); > - kernel_fpu_end(); > + > + int ret; > + atomic_t *local_fpu_ref = this_cpu_ptr(&fpu_ref); > + > + ret = atomic_dec_return(local_fpu_ref); > + TRACE_DCN_FPU(false, function_name, line, ret); > + > + if (!ret) > + kernel_fpu_end(); > } > 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)
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..cd4f0d3f37fb 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 ref_count), + TP_ARGS(begin, function, line, ref_count), TP_STRUCT__entry( __field(bool, begin) __field(const char *, function) __field(int, line) + __field(int, ref_count) ), TP_fast_assign( __entry->begin = begin; __entry->function = function; __entry->line = line; + __entry->ref_count = ref_count; ), - TP_printk("%s()+%d: %s", + TP_printk("%s: ref_count: %d: %s()+%d:", + __entry->begin ? "begin" : "end", + __entry->ref_count, __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 ff34007509de..5dcefe193523 100644 --- a/drivers/gpu/drm/amd/display/amdgpu_dm/dc_fpu.c +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/dc_fpu.c @@ -28,6 +28,19 @@ #include <asm/fpu/api.h> +/** + * DOC: 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(atomic_t, fpu_ref); + /** * dc_fpu_begin - Enables FPU protection * @function_name: A string containing the function name for debug purposes @@ -40,8 +53,14 @@ */ void dc_fpu_begin(const char *function_name, const int line) { - TRACE_DCN_FPU(true, function_name, line); - kernel_fpu_begin(); + int ret; + atomic_t *local_fpu_ref = this_cpu_ptr(&fpu_ref); + + ret = atomic_inc_return(local_fpu_ref); + TRACE_DCN_FPU(true, function_name, line, ret); + + if (ret == 1) + kernel_fpu_begin(); } /** @@ -56,6 +75,13 @@ 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); - kernel_fpu_end(); + + int ret; + atomic_t *local_fpu_ref = this_cpu_ptr(&fpu_ref); + + ret = atomic_dec_return(local_fpu_ref); + TRACE_DCN_FPU(false, function_name, line, ret); + + if (!ret) + kernel_fpu_end(); } 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)