drm/amd/display: early return if not in vga mode in disable_vga

The work around for hw bug causes S3 resume failure. Don't execute
disable vga logic if not in vga mode.

Signed-off-by: Eric Yang <[e-mail]>
Reviewed-by: Tony Cheng <[e-mail]>
Acked-by: Harry Wentland <[e-mail]>
Signed-off-by: Alex Deucher <[e-mail]>

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

···
 	HWS_SF(, DOMAIN6_PG_STATUS, DOMAIN6_PGFSM_PWR_STATUS, mask_sh), \
 	HWS_SF(, DOMAIN7_PG_STATUS, DOMAIN7_PGFSM_PWR_STATUS, mask_sh), \
 	HWS_SF(, DC_IP_REQUEST_CNTL, IP_REQUEST_EN, mask_sh), \
+	HWS_SF(, D1VGA_CONTROL, D1VGA_MODE_ENABLE, mask_sh),\
 	HWS_SF(, VGA_TEST_CONTROL, VGA_TEST_ENABLE, mask_sh),\
 	HWS_SF(, VGA_TEST_CONTROL, VGA_TEST_RENDER_START, mask_sh),\
 	HWS_SF(, LVTMA_PWRSEQ_CNTL, LVTMA_BLON, mask_sh), \
···
 	type DENTIST_DPPCLK_WDIVIDER; \
 	type DENTIST_DISPCLK_WDIVIDER; \
 	type VGA_TEST_ENABLE; \
-	type VGA_TEST_RENDER_START;
+	type VGA_TEST_RENDER_START; \
+	type D1VGA_MODE_ENABLE;
 
 struct dce_hwseq_shift {
 	HWSEQ_REG_FIELD_LIST(uint8_t)

drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hw_sequencer.c

···
 static void disable_vga(
 	struct dce_hwseq *hws)
 {
+	unsigned int in_vga_mode = 0;
+
+	REG_GET(D1VGA_CONTROL, D1VGA_MODE_ENABLE, &in_vga_mode);
+
+	if (in_vga_mode == 0)
+		return;
+
 	REG_WRITE(D1VGA_CONTROL, 0);
-	REG_WRITE(D2VGA_CONTROL, 0);
-	REG_WRITE(D3VGA_CONTROL, 0);
-	REG_WRITE(D4VGA_CONTROL, 0);
 
 	/* HW Engineer's Notes:
 	 *  During switch from vga->extended, if we set the VGA_TEST_ENABLE and