drm/amd/display: Providing a mechanism to have a custom pwm frequency

[Why]
Providing a mechanism to manipulate the pwm frequency on the
individual GPUs and monitor the transition during the switch.

[How]
Added a variable in dc_debug_options data structure. Using
this variable to call the newly added command on the firmware.
Reviewed-by: Harry Vanzylldejong <harry.vanzylldejong@amd.com>
Acked-by: Tom Chung <chiahsuan.chung@amd.com>
Signed-off-by: Sreeja Golui <sreeja.golui@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -1026,6 +1026,7 @@ struct dc_debug_options {
 	bool disable_extblankadj;
 	bool enable_idle_reg_checks;
 	unsigned int static_screen_wait_frames;
+	uint32_t pwm_freq;
 	bool force_chroma_subsampling_1tap;
 	bool disable_422_left_edge_pixel;
 	bool dml21_force_pstate_method;

drivers/gpu/drm/amd/display/dc/dcn31/dcn31_panel_cntl.c

@@ -70,6 +70,7 @@ static uint32_t dcn31_panel_cntl_hw_init(struct panel_cntl *panel_cntl)
 	struct dcn31_panel_cntl *dcn31_panel_cntl = TO_DCN31_PANEL_CNTL(panel_cntl);
 	struct dc_dmub_srv *dc_dmub_srv = panel_cntl->ctx->dmub_srv;
 	union dmub_rb_cmd cmd;
+	uint32_t freq_to_set = panel_cntl->ctx->dc->debug.pwm_freq;
 
 	if (!dc_dmub_srv)
 		return 0;
@@ -96,6 +97,19 @@ static uint32_t dcn31_panel_cntl_hw_init(struct panel_cntl *panel_cntl)
 	panel_cntl->stored_backlight_registers.PANEL_PWRSEQ_REF_DIV2 =
 		cmd.panel_cntl.data.bl_pwm_ref_div2;
 
+	if (freq_to_set >= MIN_DEBUG_FREQ_HZ && freq_to_set <= MAX_DEBUG_FREQ_HZ) {
+		uint32_t xtal = panel_cntl->ctx->dc->res_pool->ref_clocks.dccg_ref_clock_inKhz;
+
+		memset(&cmd, 0, sizeof(cmd));
+		cmd.panel_cntl.header.type = DMUB_CMD__PANEL_CNTL;
+		cmd.panel_cntl.header.sub_type = DMUB_CMD__PANEL_DEBUG_PWM_FREQ;
+		cmd.panel_cntl.header.payload_bytes = sizeof(cmd.panel_cntl.data);
+		cmd.panel_cntl.data.pwrseq_inst = dcn31_panel_cntl->base.pwrseq_inst;
+		cmd.panel_cntl.data.bl_pwm_cntl = xtal;
+		cmd.panel_cntl.data.bl_pwm_period_cntl = freq_to_set;
+		if (!dc_wake_and_execute_dmub_cmd(dc_dmub_srv->ctx, &cmd, DM_DMUB_WAIT_TYPE_WAIT_WITH_REPLY))
+			return 0;
+	}
 	return cmd.panel_cntl.data.current_backlight;
 }
 

drivers/gpu/drm/amd/display/dc/dcn31/dcn31_panel_cntl.h

@@ -29,6 +29,9 @@
 #include "panel_cntl.h"
 #include "dce/dce_panel_cntl.h"
 
+#define MIN_DEBUG_FREQ_HZ 200
+#define MAX_DEBUG_FREQ_HZ 6250
+
 struct dcn31_panel_cntl {
 	struct panel_cntl base;
 };