drm/amd/display: Add version check before using DP alt query interface

[Why]
To maintain compatibility with firmware older than 4.0.11.

Those firmware may have interrmittent hangs with RDCSPIPE or the PHY,
but we shouldn't regress their previous behavior.

[How]
Use the new path if firmware is development or 4.0.11 or newer. Use the
legacy path otherwise.

Fixes: 41f91315 ("drm/amd/display: Query DMCUB for dp alt status")
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Reviewed-by: Hansen Dsouza <hansen.dsouza@amd.com>
Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/dcn31/dcn31_dio_link_encoder.c

@@ -100,6 +100,35 @@ static uint8_t phy_id_from_transmitter(enum transmitter t)
 	return phy_id;
 }
 
+static bool has_query_dp_alt(struct link_encoder *enc)
+{
+	struct dc_dmub_srv *dc_dmub_srv = enc->ctx->dmub_srv;
+
+	/* Supports development firmware and firmware >= 4.0.11 */
+	return dc_dmub_srv &&
+	       !(dc_dmub_srv->dmub->fw_version >= DMUB_FW_VERSION(4, 0, 0) &&
+		 dc_dmub_srv->dmub->fw_version <= DMUB_FW_VERSION(4, 0, 10));
+}
+
+static bool query_dp_alt_from_dmub(struct link_encoder *enc,
+				   union dmub_rb_cmd *cmd)
+{
+	struct dcn10_link_encoder *enc10 = TO_DCN10_LINK_ENC(enc);
+	struct dc_dmub_srv *dc_dmub_srv = enc->ctx->dmub_srv;
+
+	memset(cmd, 0, sizeof(*cmd));
+	cmd->query_dp_alt.header.type = DMUB_CMD__VBIOS;
+	cmd->query_dp_alt.header.sub_type =
+		DMUB_CMD__VBIOS_TRANSMITTER_QUERY_DP_ALT;
+	cmd->query_dp_alt.header.payload_bytes = sizeof(cmd->query_dp_alt.data);
+	cmd->query_dp_alt.data.phy_id = phy_id_from_transmitter(enc10->base.transmitter);
+
+	if (!dc_dmub_srv_cmd_with_reply_data(dc_dmub_srv, cmd))
+		return false;
+
+	return true;
+}
+
 void dcn31_link_encoder_set_dio_phy_mux(
 	struct link_encoder *enc,
 	enum encoder_type_select sel,
@@ -569,45 +598,90 @@ void dcn31_link_encoder_disable_output(
 bool dcn31_link_encoder_is_in_alt_mode(struct link_encoder *enc)
 {
 	struct dcn10_link_encoder *enc10 = TO_DCN10_LINK_ENC(enc);
-	struct dc_dmub_srv *dc_dmub_srv = enc->ctx->dmub_srv;
 	union dmub_rb_cmd cmd;
-	bool is_usb_c_alt_mode = false;
+	uint32_t dp_alt_mode_disable;
 
-	if (enc->features.flags.bits.DP_IS_USB_C && dc_dmub_srv) {
-		memset(&cmd, 0, sizeof(cmd));
-		cmd.query_dp_alt.header.type = DMUB_CMD__VBIOS;
-		cmd.query_dp_alt.header.sub_type = DMUB_CMD__VBIOS_TRANSMITTER_QUERY_DP_ALT;
-		cmd.query_dp_alt.header.payload_bytes = sizeof(cmd.panel_cntl.data);
-		cmd.query_dp_alt.data.phy_id = phy_id_from_transmitter(enc10->base.transmitter);
+	/* Only applicable to USB-C PHY. */
+	if (!enc->features.flags.bits.DP_IS_USB_C)
+		return false;
 
-		if (!dc_dmub_srv_cmd_with_reply_data(dc_dmub_srv, &cmd))
+	/*
+	 * Use the new interface from DMCUB if available.
+	 * Avoids hanging the RDCPSPIPE if DMCUB wasn't already running.
+	 */
+	if (has_query_dp_alt(enc)) {
+		if (!query_dp_alt_from_dmub(enc, &cmd))
 			return false;
 
-		is_usb_c_alt_mode = (cmd.query_dp_alt.data.is_dp_alt_disable == 0);
+		return (cmd.query_dp_alt.data.is_dp_alt_disable == 0);
 	}
 
-	return is_usb_c_alt_mode;
+	/* Legacy path, avoid if possible. */
+	if (enc->ctx->asic_id.hw_internal_rev != YELLOW_CARP_B0) {
+		REG_GET(RDPCSTX_PHY_CNTL6, RDPCS_PHY_DPALT_DISABLE,
+			&dp_alt_mode_disable);
+	} else {
+		/*
+		 * B0 phys use a new set of registers to check whether alt mode is disabled.
+		 * if value == 1 alt mode is disabled, otherwise it is enabled.
+		 */
+		if ((enc10->base.transmitter == TRANSMITTER_UNIPHY_A) ||
+		    (enc10->base.transmitter == TRANSMITTER_UNIPHY_B) ||
+		    (enc10->base.transmitter == TRANSMITTER_UNIPHY_E)) {
+			REG_GET(RDPCSTX_PHY_CNTL6, RDPCS_PHY_DPALT_DISABLE,
+				&dp_alt_mode_disable);
+		} else {
+			REG_GET(RDPCSPIPE_PHY_CNTL6, RDPCS_PHY_DPALT_DISABLE,
+				&dp_alt_mode_disable);
+		}
+	}
+
+	return (dp_alt_mode_disable == 0);
 }
 
 void dcn31_link_encoder_get_max_link_cap(struct link_encoder *enc, struct dc_link_settings *link_settings)
 {
 	struct dcn10_link_encoder *enc10 = TO_DCN10_LINK_ENC(enc);
-	struct dc_dmub_srv *dc_dmub_srv = enc->ctx->dmub_srv;
 	union dmub_rb_cmd cmd;
+	uint32_t is_in_usb_c_dp4_mode = 0;
 
 	dcn10_link_encoder_get_max_link_cap(enc, link_settings);
 
-	if (enc->features.flags.bits.DP_IS_USB_C && dc_dmub_srv) {
-		memset(&cmd, 0, sizeof(cmd));
-		cmd.query_dp_alt.header.type = DMUB_CMD__VBIOS;
-		cmd.query_dp_alt.header.sub_type = DMUB_CMD__VBIOS_TRANSMITTER_QUERY_DP_ALT;
-		cmd.query_dp_alt.header.payload_bytes = sizeof(cmd.panel_cntl.data);
-		cmd.query_dp_alt.data.phy_id = phy_id_from_transmitter(enc10->base.transmitter);
+	/* Take the link cap directly if not USB */
+	if (!enc->features.flags.bits.DP_IS_USB_C)
+		return;
 
-		if (!dc_dmub_srv_cmd_with_reply_data(dc_dmub_srv, &cmd))
+	/*
+	 * Use the new interface from DMCUB if available.
+	 * Avoids hanging the RDCPSPIPE if DMCUB wasn't already running.
+	 */
+	if (has_query_dp_alt(enc)) {
+		if (!query_dp_alt_from_dmub(enc, &cmd))
 			return;
 
-		if (cmd.query_dp_alt.data.is_usb && cmd.query_dp_alt.data.is_dp4 == 0)
+		if (cmd.query_dp_alt.data.is_usb &&
+		    cmd.query_dp_alt.data.is_dp4 == 0)
 			link_settings->lane_count = MIN(LANE_COUNT_TWO, link_settings->lane_count);
+
+		return;
 	}
+
+	/* Legacy path, avoid if possible. */
+	if (enc->ctx->asic_id.hw_internal_rev != YELLOW_CARP_B0) {
+		REG_GET(RDPCSTX_PHY_CNTL6, RDPCS_PHY_DPALT_DP4,
+			&is_in_usb_c_dp4_mode);
+	} else {
+		if ((enc10->base.transmitter == TRANSMITTER_UNIPHY_A) ||
+		    (enc10->base.transmitter == TRANSMITTER_UNIPHY_B) ||
+		    (enc10->base.transmitter == TRANSMITTER_UNIPHY_E)) {
+			REG_GET(RDPCSTX_PHY_CNTL6, RDPCS_PHY_DPALT_DP4,
+				&is_in_usb_c_dp4_mode);
+		} else {
+			REG_GET(RDPCSPIPE_PHY_CNTL6, RDPCS_PHY_DPALT_DP4,
+				&is_in_usb_c_dp4_mode);
+		}
+	}
+
+	if (!is_in_usb_c_dp4_mode)
+		link_settings->lane_count = MIN(LANE_COUNT_TWO, link_settings->lane_count);
 }