drm/amd/display: Delete dead code in command_table_helper

[Why]
dig_encoder_sel_to_atom will always return zero on any ASIC version
past DCE80 since programming of the FE selection is handled by
driver, but the translation code was left in the function, making
it look like a coding error.

[How]
Remove code that has no effect, and replace with a comment describing
why it returns zero.
Signed-off-by: Julian Parkin <julian.parkin@amd.com>
Reviewed-by: Wenjing Liu <Wenjing.Liu@amd.com>
Acked-by: Bhawanpreet Lakha <Bhawanpreet.Lakha@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/bios/dce110/command_table_helper_dce110.c

@@ -153,38 +153,10 @@ static uint8_t hpd_sel_to_atom(enum hpd_source_id id)
 
 static uint8_t dig_encoder_sel_to_atom(enum engine_id id)
 {
-	uint8_t atom_dig_encoder_sel = 0;
-
-	switch (id) {
-	case ENGINE_ID_DIGA:
-		atom_dig_encoder_sel = ATOM_TRANMSITTER_V5__DIGA_SEL;
-		break;
-	case ENGINE_ID_DIGB:
-		atom_dig_encoder_sel = ATOM_TRANMSITTER_V5__DIGB_SEL;
-		break;
-	case ENGINE_ID_DIGC:
-		atom_dig_encoder_sel = ATOM_TRANMSITTER_V5__DIGC_SEL;
-		break;
-	case ENGINE_ID_DIGD:
-		atom_dig_encoder_sel = ATOM_TRANMSITTER_V5__DIGD_SEL;
-		break;
-	case ENGINE_ID_DIGE:
-		atom_dig_encoder_sel = ATOM_TRANMSITTER_V5__DIGE_SEL;
-		break;
-	case ENGINE_ID_DIGF:
-		atom_dig_encoder_sel = ATOM_TRANMSITTER_V5__DIGF_SEL;
-		break;
-	case ENGINE_ID_DIGG:
-		atom_dig_encoder_sel = ATOM_TRANMSITTER_V5__DIGG_SEL;
-		break;
-	case ENGINE_ID_UNKNOWN:
-		 /* No DIG_FRONT is associated to DIG_BACKEND */
-		atom_dig_encoder_sel = 0;
-		break;
-	default:
-		atom_dig_encoder_sel = ATOM_TRANMSITTER_V5__DIGA_SEL;
-		break;
-	}
+	/* On any ASIC after DCE80, we manually program the DIG_FE
+	 * selection (see connect_dig_be_to_fe function of the link
+	 * encoder), so translation should always return 0 (no FE).
+	 */
 
 	return 0;
 }

drivers/gpu/drm/amd/display/dc/bios/dce112/command_table_helper2_dce112.c

@@ -150,38 +150,10 @@ static uint8_t hpd_sel_to_atom(enum hpd_source_id id)
 
 static uint8_t dig_encoder_sel_to_atom(enum engine_id id)
 {
-	uint8_t atom_dig_encoder_sel = 0;
-
-	switch (id) {
-	case ENGINE_ID_DIGA:
-		atom_dig_encoder_sel = ATOM_TRANMSITTER_V6__DIGA_SEL;
-		break;
-	case ENGINE_ID_DIGB:
-		atom_dig_encoder_sel = ATOM_TRANMSITTER_V6__DIGB_SEL;
-		break;
-	case ENGINE_ID_DIGC:
-		atom_dig_encoder_sel = ATOM_TRANMSITTER_V6__DIGC_SEL;
-		break;
-	case ENGINE_ID_DIGD:
-		atom_dig_encoder_sel = ATOM_TRANMSITTER_V6__DIGD_SEL;
-		break;
-	case ENGINE_ID_DIGE:
-		atom_dig_encoder_sel = ATOM_TRANMSITTER_V6__DIGE_SEL;
-		break;
-	case ENGINE_ID_DIGF:
-		atom_dig_encoder_sel = ATOM_TRANMSITTER_V6__DIGF_SEL;
-		break;
-	case ENGINE_ID_DIGG:
-		atom_dig_encoder_sel = ATOM_TRANMSITTER_V6__DIGG_SEL;
-		break;
-	case ENGINE_ID_UNKNOWN:
-		/* No DIG_FRONT is associated to DIG_BACKEND */
-		atom_dig_encoder_sel = 0;
-		break;
-	default:
-		atom_dig_encoder_sel = ATOM_TRANMSITTER_V6__DIGA_SEL;
-		break;
-	}
+	/* On any ASIC after DCE80, we manually program the DIG_FE
+	 * selection (see connect_dig_be_to_fe function of the link
+	 * encoder), so translation should always return 0 (no FE).
+	 */
 
 	return 0;
 }

drivers/gpu/drm/amd/display/dc/bios/dce112/command_table_helper_dce112.c

@@ -150,38 +150,10 @@ static uint8_t hpd_sel_to_atom(enum hpd_source_id id)
 
 static uint8_t dig_encoder_sel_to_atom(enum engine_id id)
 {
-	uint8_t atom_dig_encoder_sel = 0;
-
-	switch (id) {
-	case ENGINE_ID_DIGA:
-		atom_dig_encoder_sel = ATOM_TRANMSITTER_V6__DIGA_SEL;
-		break;
-	case ENGINE_ID_DIGB:
-		atom_dig_encoder_sel = ATOM_TRANMSITTER_V6__DIGB_SEL;
-		break;
-	case ENGINE_ID_DIGC:
-		atom_dig_encoder_sel = ATOM_TRANMSITTER_V6__DIGC_SEL;
-		break;
-	case ENGINE_ID_DIGD:
-		atom_dig_encoder_sel = ATOM_TRANMSITTER_V6__DIGD_SEL;
-		break;
-	case ENGINE_ID_DIGE:
-		atom_dig_encoder_sel = ATOM_TRANMSITTER_V6__DIGE_SEL;
-		break;
-	case ENGINE_ID_DIGF:
-		atom_dig_encoder_sel = ATOM_TRANMSITTER_V6__DIGF_SEL;
-		break;
-	case ENGINE_ID_DIGG:
-		atom_dig_encoder_sel = ATOM_TRANMSITTER_V6__DIGG_SEL;
-		break;
-	case ENGINE_ID_UNKNOWN:
-		/* No DIG_FRONT is associated to DIG_BACKEND */
-		atom_dig_encoder_sel = 0;
-		break;
-	default:
-		atom_dig_encoder_sel = ATOM_TRANMSITTER_V6__DIGA_SEL;
-		break;
-	}
+	/* On any ASIC after DCE80, we manually program the DIG_FE
+	 * selection (see connect_dig_be_to_fe function of the link
+	 * encoder), so translation should always return 0 (no FE).
+	 */
 
 	return 0;
 }