drm/amd/display: Bug in dce_is_panel_backlight_on()

[Why]
dce_is_panel_backlight_on() will return wrong value if
LVTMA_BLON_OVRD is 0

[How]
When LVTMA_BLON_OVRD is 0, read
LVTMA_PWRSEQ_TARGET_STATE instead

Signed-off-by: Peikang Zhang <[e-mail]>
Reviewed-by: Anthony Koo <[e-mail]>
Acked-by: Qingqing Zhuo <[e-mail]>
Signed-off-by: Alex Deucher <[e-mail]>

drivers/gpu/drm/amd/display/dc/dce/dce_panel_cntl.c

···
 static bool dce_is_panel_backlight_on(struct panel_cntl *panel_cntl)
 {
 	struct dce_panel_cntl *dce_panel_cntl = TO_DCE_PANEL_CNTL(panel_cntl);
-	uint32_t value;
+	uint32_t blon, blon_ovrd, pwrseq_target_state;
 
-	REG_GET(PWRSEQ_CNTL, LVTMA_BLON, &value);
+	REG_GET_2(PWRSEQ_CNTL, LVTMA_BLON, &blon, LVTMA_BLON_OVRD, &blon_ovrd);
+	REG_GET(PWRSEQ_CNTL, LVTMA_PWRSEQ_TARGET_STATE, &pwrseq_target_state);
 
-	return value;
+	if (blon_ovrd)
+		return blon;
+	else
+		return pwrseq_target_state;
 }
 
 static bool dce_is_panel_powered_on(struct panel_cntl *panel_cntl)

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

···
 
 #define DCE_PANEL_CNTL_MASK_SH_LIST(mask_sh) \
 	DCE_PANEL_CNTL_SF(LVTMA_PWRSEQ_CNTL, LVTMA_BLON, mask_sh),\
+	DCE_PANEL_CNTL_SF(LVTMA_PWRSEQ_CNTL, LVTMA_BLON_OVRD, mask_sh),\
 	DCE_PANEL_CNTL_SF(LVTMA_PWRSEQ_CNTL, LVTMA_DIGON, mask_sh),\
 	DCE_PANEL_CNTL_SF(LVTMA_PWRSEQ_CNTL, LVTMA_DIGON_OVRD, mask_sh),\
+	DCE_PANEL_CNTL_SF(LVTMA_PWRSEQ_CNTL, LVTMA_PWRSEQ_TARGET_STATE, mask_sh), \
 	DCE_PANEL_CNTL_SF(LVTMA_PWRSEQ_STATE, LVTMA_PWRSEQ_TARGET_STATE_R, mask_sh), \
 	DCE_PANEL_CNTL_SF(LVTMA_PWRSEQ_REF_DIV, BL_PWM_REF_DIV, mask_sh), \
 	DCE_PANEL_CNTL_SF(BL_PWM_PERIOD_CNTL, BL_PWM_PERIOD, mask_sh), \
···
 
 #define DCE_PANEL_CNTL_REG_FIELD_LIST(type) \
 	type LVTMA_BLON;\
+	type LVTMA_BLON_OVRD;\
 	type LVTMA_DIGON;\
 	type LVTMA_DIGON_OVRD;\
+	type LVTMA_PWRSEQ_TARGET_STATE; \
 	type LVTMA_PWRSEQ_TARGET_STATE_R; \
 	type BL_PWM_REF_DIV; \
 	type BL_PWM_EN; \