Commit 2d8471dc authored by Rodrigo Siqueira's avatar Rodrigo Siqueira Committed by Alex Deucher
Browse files

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



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: default avatarkernel test robot <lkp@intel.com>
Signed-off-by: default avatarRodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Reviewed-by: default avatarChristian König <christian.koenig@amd.com>
Signed-off-by: default avatarAlex Deucher <alexander.deucher@amd.com>
parent 96ee6373

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_trace.h

+8 −5
Original line number Diff line number Diff line
@@ -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

	    )

);

drivers/gpu/drm/amd/display/amdgpu_dm/dc_fpu.c

+53 −24
Original line number Diff line number Diff line
@@ -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
@@ -48,8 +61,12 @@ 
 */

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();

#elif defined(CONFIG_PPC64)
@@ -66,6 +83,10 @@ void dc_fpu_begin(const char *function_name, const int line) 
#endif

	}



	TRACE_DCN_FPU(true, function_name, line, *pcpu);

	put_cpu_ptr(&fpu_recursion_depth);

}



/**

 * dc_fpu_end - Disable FPU protection

 * @function_name: A string containing the function name for debug purposes
@@ -78,7 +99,11 @@ 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();

#elif defined(CONFIG_PPC64)
@@ -94,3 +119,7 @@ void dc_fpu_end(const char *function_name, const int line) 
		}

#endif

	}



	TRACE_DCN_FPU(false, function_name, line, *pcpu);

	put_cpu_ptr(&fpu_recursion_depth);

}

drivers/gpu/drm/amd/display/dc/dc_trace.h

+2 −2
Original line number Diff line number Diff line
@@ -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)