drm/amd/display: Support for DMUB AUX

[WHY]
To process AUX transactions with DMUB using inbox1 and outbox1 mail boxes.

[HOW]
1) Added inbox1 command DMUB_CMD__DP_AUX_ACCESS to issue AUX commands
to DMUB in dc_process_dmub_aux_transfer_async(). DMUB processes AUX cmd
with DCN and sends reply back in an outbox1 message triggering an
outbox1 interrupt to driver.
2) In existing driver implementation, AUX commands are processed
synchronously by configuring DCN reg. But in DMUB AUX, driver sends an
inbox1 message and waits for a conditional variable (CV) which will be
signaled by outbox1 ISR.
3) As the driver holds dal and dc locks while waiting for CV, the outbox1
ISR is registered with noMutexWait set to true, which allows ISR to run
and signal CV. This sets a constraint on ISR to not modify variables
such as dc, dmub, etc.
4) Created dmub_outbox.c with dmub_enable_outbox_notification() to enable
outbox1 mailbox.
5) New mailbox address ranges allocated for outbox1 of size DMUB_RB_SIZE.
Created dmub functions for Outbox1: dmub_dcn20_setup_out_mailbox(),
dmub_dcn20_get_outbox1_wptr() and dmub_dcn20_set_outbox1_rptr().
6) Added functions dc_stat_get_dmub_notification() and
dmub_srv_stat_get_notification() to retrieve Outbox1 message.
7) Currently, DMUB doesn't opens DDC in AUX mode before issuing AUX
transaction. A workaround is added in dce_aux_transfer_dmub_raw() to
open in DDC in AUX mode for every AUX transaction.
8) Added dc debug option enable_dmub_aux_for_legacy_ddc enable/disable
DMUB AUX. This debug option is checked dce_aux_transfer_with_retries()
to select the method to process AUX transactions.

Tested-by: Daniel Wheeler <[e-mail]>
Signed-off-by: Meenakshikumar Somasundaram <[e-mail]>
Reviewed-by: Jun Lei <[e-mail]>
Acked-by: Rodrigo Siqueira <[e-mail]>
Signed-off-by: Alex Deucher <[e-mail]>

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c

···
 #include "dc_link_ddc.h"
 
 #include "i2caux_interface.h"
+#include "dmub_cmd.h"
 #if defined(CONFIG_DEBUG_FS)
 #include "amdgpu_dm_debugfs.h"
 #endif
···
 {
 	ssize_t result = 0;
 	struct aux_payload payload;
-	enum aux_channel_operation_result operation_result;
+	enum aux_return_code_type operation_result;
 
 	if (WARN_ON(msg->size > 16))
 		return -E2BIG;
···
 
 	if (result < 0)
 		switch (operation_result) {
-		case AUX_CHANNEL_OPERATION_SUCCEEDED:
+		case AUX_RET_SUCCESS:
 			break;
-		case AUX_CHANNEL_OPERATION_FAILED_HPD_DISCON:
-		case AUX_CHANNEL_OPERATION_FAILED_REASON_UNKNOWN:
+		case AUX_RET_ERROR_HPD_DISCON:
+		case AUX_RET_ERROR_UNKNOWN:
+		case AUX_RET_ERROR_INVALID_OPERATION:
+		case AUX_RET_ERROR_PROTOCOL_ERROR:
 			result = -EIO;
 			break;
-		case AUX_CHANNEL_OPERATION_FAILED_INVALID_REPLY:
-		case AUX_CHANNEL_OPERATION_FAILED_ENGINE_ACQUIRE:
+		case AUX_RET_ERROR_INVALID_REPLY:
+		case AUX_RET_ERROR_ENGINE_ACQUIRE:
 			result = -EBUSY;
 			break;
-		case AUX_CHANNEL_OPERATION_FAILED_TIMEOUT:
+		case AUX_RET_ERROR_TIMEOUT:
 			result = -ETIMEDOUT;
 			break;
 		}

drivers/gpu/drm/amd/display/dc/Makefile

···
 
 include $(AMD_DC)
 
-DISPLAY_CORE = dc.o dc_link.o dc_resource.o dc_hw_sequencer.o dc_sink.o \
+DISPLAY_CORE = dc.o dc_stat.o dc_link.o dc_resource.o dc_hw_sequencer.o dc_sink.o \
 dc_surface.o dc_link_hwss.o dc_link_dp.o dc_link_ddc.o dc_debug.o dc_stream.o
 
 ifdef CONFIG_DRM_AMD_DC_DCN

drivers/gpu/drm/amd/display/dc/core/dc.c

···
 
 #include "dmub/dmub_srv.h"
 
+#include "i2caux_interface.h"
 #include "dce/dmub_hw_lock_mgr.h"
 
 #include "dc_trace.h"
···
 		dc->hwss.hardware_release(dc);
 }
 #endif
+
+/**
+ *****************************************************************************
+ *  Function: dc_enable_dmub_notifications
+ *
+ *  @brief
+ *		Returns whether dmub notification can be enabled
+ *
+ *  @param
+ *		[in] dc: dc structure
+ *
+ *	@return
+ *		True to enable dmub notifications, False otherwise
+ *****************************************************************************
+ */
+bool dc_enable_dmub_notifications(struct dc *dc)
+{
+	/* dmub aux needs dmub notifications to be enabled */
+	return dc->debug.enable_dmub_aux_for_legacy_ddc;
+}
+
+/**
+ *****************************************************************************
+ *  Function: dc_process_dmub_aux_transfer_async
+ *
+ *  @brief
+ *		Submits aux command to dmub via inbox message
+ *		Sets port index appropriately for legacy DDC
+ *
+ *  @param
+ *		[in] dc: dc structure
+ *		[in] link_index: link index
+ *		[in] payload: aux payload
+ *
+ *	@return
+ *		True if successful, False if failure
+ *****************************************************************************
+ */
+bool dc_process_dmub_aux_transfer_async(struct dc *dc,
+				uint32_t link_index,
+				struct aux_payload *payload)
+{
+	uint8_t action;
+	union dmub_rb_cmd cmd = {0};
+	struct dc_dmub_srv *dmub_srv = dc->ctx->dmub_srv;
+
+	ASSERT(payload->length <= 16);
+
+	cmd.dp_aux_access.header.type = DMUB_CMD__DP_AUX_ACCESS;
+	cmd.dp_aux_access.header.payload_bytes = 0;
+	cmd.dp_aux_access.aux_control.type = AUX_CHANNEL_LEGACY_DDC;
+	cmd.dp_aux_access.aux_control.instance = dc->links[link_index]->ddc_hw_inst;
+	cmd.dp_aux_access.aux_control.sw_crc_enabled = 0;
+	cmd.dp_aux_access.aux_control.timeout = 0;
+	cmd.dp_aux_access.aux_control.dpaux.address = payload->address;
+	cmd.dp_aux_access.aux_control.dpaux.is_i2c_over_aux = payload->i2c_over_aux;
+	cmd.dp_aux_access.aux_control.dpaux.length = payload->length;
+
+	/* set aux action */
+	if (payload->i2c_over_aux) {
+		if (payload->write) {
+			if (payload->mot)
+				action = DP_AUX_REQ_ACTION_I2C_WRITE_MOT;
+			else
+				action = DP_AUX_REQ_ACTION_I2C_WRITE;
+		} else {
+			if (payload->mot)
+				action = DP_AUX_REQ_ACTION_I2C_READ_MOT;
+			else
+				action = DP_AUX_REQ_ACTION_I2C_READ;
+			}
+	} else {
+		if (payload->write)
+			action = DP_AUX_REQ_ACTION_DPCD_WRITE;
+		else
+			action = DP_AUX_REQ_ACTION_DPCD_READ;
+	}
+
+	cmd.dp_aux_access.aux_control.dpaux.action = action;
+
+	if (payload->length && payload->write) {
+		memcpy(cmd.dp_aux_access.aux_control.dpaux.data,
+			payload->data,
+			payload->length
+			);
+	}
+
+	dc_dmub_srv_cmd_queue(dmub_srv, &cmd);
+	dc_dmub_srv_cmd_execute(dmub_srv);
+	dc_dmub_srv_wait_idle(dmub_srv);
+
+	return true;
+}

drivers/gpu/drm/amd/display/dc/core/dc_link_ddc.c

···
 #include "core_types.h"
 #include "dc_link_ddc.h"
 #include "dce/dce_aux.h"
+#include "dmub/inc/dmub_cmd.h"
 
 #define DC_LOGGER_INIT(logger)
 
···
  */
 int dc_link_aux_transfer_raw(struct ddc_service *ddc,
 		struct aux_payload *payload,
-		enum aux_channel_operation_result *operation_result)
+		enum aux_return_code_type *operation_result)
 {
 	return dce_aux_transfer_raw(ddc, payload, operation_result);
 }

drivers/gpu/drm/amd/display/dc/core/dc_stat.c

···
+/*
+ * Copyright 2020 Advanced Micro Devices, Inc.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
+ * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+ * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ *
+ * Authors: AMD
+ */
+
+#include "dc/dc_stat.h"
+#include "dmub/dmub_srv_stat.h"
+#include "dc_dmub_srv.h"
+
+/**
+ * DOC: DC STAT Interface
+ *
+ * These interfaces are called without acquiring DAL and DC locks.
+ * Hence, there is limitations on whese interfaces can access. Only
+ * variables exclusively defined for these interfaces can be modified.
+ */
+
+/**
+ *****************************************************************************
+ *  Function: dc_stat_get_dmub_notification
+ *
+ *  @brief
+ *		Calls dmub layer to retrieve dmub notification
+ *
+ *  @param
+ *		[in] dc: dc structure
+ *		[in] notify: dmub notification structure
+ *
+ *  @return
+ *     None
+ *****************************************************************************
+ */
+void dc_stat_get_dmub_notification(const struct dc *dc, struct dmub_notification *notify)
+{
+	/**
+	 * This function is called without dal and dc locks, so
+	 * we shall not modify any dc, dc_dmub_srv or dmub variables
+	 * except variables exclusively accessed by this function
+	 */
+	struct dmub_srv *dmub = dc->ctx->dmub_srv->dmub;
+	enum dmub_status status;
+
+	status = dmub_srv_stat_get_notification(dmub, notify);
+	ASSERT(status == DMUB_STATUS_OK);
+}

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

···
 #include "inc/hw/dmcu.h"
 #include "dml/display_mode_lib.h"
 
+/* forward declaration */
+struct aux_payload;
+
 #define DC_VER "3.2.124"
 
 #define MAX_SURFACES 3
···
 	bool enable_dram_clock_change_one_display_vactive;
 	union mem_low_power_enable_options enable_mem_low_power;
 	bool force_vblank_alignment;
+
+	/* Enable dmub aux for legacy ddc */
+	bool enable_dmub_aux_for_legacy_ddc;
 };
 
 struct dc_debug_data {
···
 #endif
 
 bool dc_set_psr_allow_active(struct dc *dc, bool enable);
+
+bool dc_enable_dmub_notifications(struct dc *dc);
+
+bool dc_process_dmub_aux_transfer_async(struct dc *dc,
+				uint32_t link_index,
+				struct aux_payload *payload);
 
 /*******************************************************************************
  * DSC Interfaces

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

···
 	I2CAUX_TRANSACTION_ACTION_DP_READ = 0x90
 };
 
-enum aux_channel_operation_result {
-	AUX_CHANNEL_OPERATION_SUCCEEDED,
-	AUX_CHANNEL_OPERATION_FAILED_REASON_UNKNOWN,
-	AUX_CHANNEL_OPERATION_FAILED_INVALID_REPLY,
-	AUX_CHANNEL_OPERATION_FAILED_TIMEOUT,
-	AUX_CHANNEL_OPERATION_FAILED_HPD_DISCON,
-	AUX_CHANNEL_OPERATION_FAILED_ENGINE_ACQUIRE
-};
-
-
 struct aux_request_transaction_data {
 	enum aux_transaction_type type;
 	enum i2caux_transaction_action action;

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

···
+/*
+ * Copyright 2020 Advanced Micro Devices, Inc.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
+ * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+ * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ *
+ * Authors: AMD
+ *
+ */
+
+#ifndef _DC_STAT_H_
+#define _DC_STAT_H_
+
+/**
+ * DOC: DC STAT Interface
+ *
+ * These interfaces are called without acquiring DAL and DC locks.
+ * Hence, there is limitations on whese interfaces can access. Only
+ * variables exclusively defined for these interfaces can be modified.
+ */
+
+#include "dc.h"
+#include "dmub/dmub_srv.h"
+
+void dc_stat_get_dmub_notification(const struct dc *dc, struct dmub_notification *notify);
+
+#endif /* _DC_STAT_H_ */

drivers/gpu/drm/amd/display/dc/dce/Makefile

···
 dce_mem_input.o dce_clock_source.o dce_scl_filters.o dce_transform.o \
 dce_opp.o dce_dmcu.o dce_abm.o dce_ipp.o dce_aux.o \
 dce_i2c.o dce_i2c_hw.o dce_i2c_sw.o dmub_psr.o dmub_abm.o dce_panel_cntl.o \
-dmub_hw_lock_mgr.o
+dmub_hw_lock_mgr.o dmub_outbox.o
 
 AMD_DAL_DCE = $(addprefix $(AMDDALPATH)/dc/dce/,$(DCE))
 

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

···
 #include "dce_aux.h"
 #include "dce/dce_11_0_sh_mask.h"
 #include "dm_event_log.h"
+#include "dm_helpers.h"
+#include "dmub/inc/dmub_cmd.h"
 
 #define CTX \
 	aux110->base.ctx
···
 	return 0;
 }
 
-static enum aux_channel_operation_result get_channel_status(
+static enum aux_return_code_type get_channel_status(
 	struct dce_aux *engine,
 	uint8_t *returned_bytes)
 {
···
 	if (returned_bytes == NULL) {
 		/*caller pass NULL pointer*/
 		ASSERT_CRITICAL(false);
-		return AUX_CHANNEL_OPERATION_FAILED_REASON_UNKNOWN;
+		return AUX_RET_ERROR_UNKNOWN;
 	}
 	*returned_bytes = 0;
 
···
 	value = REG_READ(AUX_SW_STATUS);
 	/* in case HPD is LOW, exit AUX transaction */
 	if ((value & AUX_SW_STATUS__AUX_SW_HPD_DISCON_MASK))
-		return AUX_CHANNEL_OPERATION_FAILED_HPD_DISCON;
+		return AUX_RET_ERROR_HPD_DISCON;
 
 	/* Note that the following bits are set in 'status.bits'
 	 * during CTS 4.2.1.2 (FW 3.3.1):
···
 	if (value & AUX_SW_STATUS__AUX_SW_DONE_MASK) {
 		if ((value & AUX_SW_STATUS__AUX_SW_RX_TIMEOUT_STATE_MASK) ||
 			(value & AUX_SW_STATUS__AUX_SW_RX_TIMEOUT_MASK))
-			return AUX_CHANNEL_OPERATION_FAILED_TIMEOUT;
+			return AUX_RET_ERROR_TIMEOUT;
 
 		else if ((value & AUX_SW_STATUS__AUX_SW_RX_INVALID_STOP_MASK) ||
 			(value & AUX_SW_STATUS__AUX_SW_RX_RECV_NO_DET_MASK) ||
 			(value &
 				AUX_SW_STATUS__AUX_SW_RX_RECV_INVALID_H_MASK) ||
 			(value & AUX_SW_STATUS__AUX_SW_RX_RECV_INVALID_L_MASK))
-			return AUX_CHANNEL_OPERATION_FAILED_INVALID_REPLY;
+			return AUX_RET_ERROR_INVALID_REPLY;
 
 		*returned_bytes = get_reg_field_value(value,
 				AUX_SW_STATUS,
···
 
 		if (*returned_bytes == 0)
 			return
-			AUX_CHANNEL_OPERATION_FAILED_INVALID_REPLY;
+			AUX_RET_ERROR_INVALID_REPLY;
 		else {
 			*returned_bytes -= 1;
-			return AUX_CHANNEL_OPERATION_SUCCEEDED;
+			return AUX_RET_SUCCESS;
 		}
 	} else {
 		/*time_elapsed >= aux_engine->timeout_period
 		 *  AUX_SW_STATUS__AUX_SW_HPD_DISCON = at this point
 		 */
 		ASSERT_CRITICAL(false);
-		return AUX_CHANNEL_OPERATION_FAILED_TIMEOUT;
+		return AUX_RET_ERROR_TIMEOUT;
 	}
 }
 
···
 
 int dce_aux_transfer_raw(struct ddc_service *ddc,
 		struct aux_payload *payload,
-		enum aux_channel_operation_result *operation_result)
+		enum aux_return_code_type *operation_result)
 {
 	struct ddc *ddc_pin = ddc->ddc_pin;
 	struct dce_aux *aux_engine;
···
 
 	aux_engine = ddc->ctx->dc->res_pool->engines[ddc_pin->pin_data->en];
 	if (!acquire(aux_engine, ddc_pin)) {
-		*operation_result = AUX_CHANNEL_OPERATION_FAILED_ENGINE_ACQUIRE;
+		*operation_result = AUX_RET_ERROR_ENGINE_ACQUIRE;
 		return -1;
 	}
 
···
 	submit_channel_request(aux_engine, &aux_req);
 	*operation_result = get_channel_status(aux_engine, &returned_bytes);
 
-	if (*operation_result == AUX_CHANNEL_OPERATION_SUCCEEDED) {
+	if (*operation_result == AUX_RET_SUCCESS) {
 		int __maybe_unused bytes_replied = 0;
+
 		bytes_replied = read_channel_reply(aux_engine, payload->length,
 					 payload->data, payload->reply,
 					 &status);
···
 	int i, ret = 0;
 	uint8_t reply;
 	bool payload_reply = true;
-	enum aux_channel_operation_result operation_result;
+	enum aux_return_code_type operation_result;
 	bool retry_on_defer = false;
 
 	int aux_ack_retries = 0,
···
 
 	for (i = 0; i < AUX_MAX_RETRIES; i++) {
 		ret = dce_aux_transfer_raw(ddc, payload, &operation_result);
+
 		switch (operation_result) {
-		case AUX_CHANNEL_OPERATION_SUCCEEDED:
+		case AUX_RET_SUCCESS:
 			aux_timeout_retries = 0;
 			aux_invalid_reply_retries = 0;
 
···
 			}
 			break;
 
-		case AUX_CHANNEL_OPERATION_FAILED_INVALID_REPLY:
+		case AUX_RET_ERROR_INVALID_REPLY:
 			if (++aux_invalid_reply_retries >= AUX_MAX_INVALID_REPLY_RETRIES)
 				goto fail;
 			else
 				udelay(400);
 			break;
 
-		case AUX_CHANNEL_OPERATION_FAILED_TIMEOUT:
+		case AUX_RET_ERROR_TIMEOUT:
 			// Check whether a DEFER had occurred before the timeout.
 			// If so, treat timeout as a DEFER.
 			if (retry_on_defer) {
···
 			}
 			break;
 
-		case AUX_CHANNEL_OPERATION_FAILED_HPD_DISCON:
-		case AUX_CHANNEL_OPERATION_FAILED_ENGINE_ACQUIRE:
-		case AUX_CHANNEL_OPERATION_FAILED_REASON_UNKNOWN:
+		case AUX_RET_ERROR_HPD_DISCON:
+		case AUX_RET_ERROR_ENGINE_ACQUIRE:
+		case AUX_RET_ERROR_UNKNOWN:
 		default:
 			goto fail;
 		}

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

···
 #include "i2caux_interface.h"
 #include "inc/hw/aux_engine.h"
 
+enum aux_return_code_type;
 
 #define AUX_COMMON_REG_LIST0(id)\
 	SRI(AUX_CONTROL, DP_AUX, id), \
···
 
 int dce_aux_transfer_raw(struct ddc_service *ddc,
 		struct aux_payload *cmd,
-		enum aux_channel_operation_result *operation_result);
+		enum aux_return_code_type *operation_result);
 
 bool dce_aux_transfer_with_retries(struct ddc_service *ddc,
 		struct aux_payload *cmd);

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

···
+/*
+ * Copyright 2020 Advanced Micro Devices, Inc.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
+ * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+ * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ *
+ * Authors: AMD
+ */
+
+#include "dmub_outbox.h"
+#include "dc_dmub_srv.h"
+#include "dmub/inc/dmub_cmd.h"
+
+/**
+ *****************************************************************************
+ *  Function: dmub_enable_outbox_notification
+ *
+ *  @brief
+ *		Sends inbox cmd to dmub to enable outbox1 messages with interrupt.
+ *		Dmub sends outbox1 message and triggers outbox1 interrupt.
+ *
+ *  @param
+ *		[in] dc: dc structure
+ *
+ *  @return
+ *     None
+ *****************************************************************************
+ */
+void dmub_enable_outbox_notification(struct dc *dc)
+{
+	union dmub_rb_cmd cmd;
+	struct dc_context *dc_ctx = dc->ctx;
+
+	memset(&cmd, 0x0, sizeof(cmd));
+	cmd.outbox1_enable.header.type = DMUB_CMD__OUTBOX1_ENABLE;
+	cmd.outbox1_enable.header.sub_type = 0;
+	cmd.outbox1_enable.header.payload_bytes =
+		sizeof(cmd.outbox1_enable) -
+		sizeof(cmd.outbox1_enable.header);
+	cmd.outbox1_enable.enable = true;
+
+	dc_dmub_srv_cmd_queue(dc_ctx->dmub_srv, &cmd);
+	dc_dmub_srv_cmd_execute(dc_ctx->dmub_srv);
+	dc_dmub_srv_wait_idle(dc_ctx->dmub_srv);
+}

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

···
+/*
+ * Copyright 2020 Advanced Micro Devices, Inc.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
+ * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+ * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ *
+ * Authors: AMD
+ *
+ */
+
+#ifndef _DMUB_OUTBOX_H_
+#define _DMUB_OUTBOX_H_
+
+#include "dc.h"
+
+void dmub_enable_outbox_notification(struct dc *dc);
+
+#endif /* _DMUB_OUTBOX_H_ */

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

···
 #include "dsc.h"
 #include "dce/dmub_hw_lock_mgr.h"
 #include "dc_trace.h"
+#include "dce/dmub_outbox.h"
 
 #define DC_LOGGER_INIT(logger)
 
···
 			if (hws->funcs.dsc_pg_control != NULL)
 				hws->funcs.dsc_pg_control(hws, res_pool->dscs[i]->inst, false);
 	}
+
+	/* Enable outbox notification feature of dmub */
+	if (dc->debug.enable_dmub_aux_for_legacy_ddc)
+		dmub_enable_outbox_notification(dc);
 
 	/* we want to turn off all dp displays before doing detection */
 	if (dc->config.power_down_display_on_boot) {

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

···
 
 struct i2c_payloads;
 struct aux_payloads;
+enum aux_return_code_type;
 
 void dal_ddc_i2c_payloads_add(
 		struct i2c_payloads *payloads,
···
 
 int dc_link_aux_transfer_raw(struct ddc_service *ddc,
 		struct aux_payload *payload,
-		enum aux_channel_operation_result *operation_result);
+		enum aux_return_code_type *operation_result);
 
 bool dc_link_aux_transfer_with_retries(struct ddc_service *ddc,
 		struct aux_payload *payload);

drivers/gpu/drm/amd/display/dc/inc/hw/aux_engine.h

···
 #include "dc_ddc_types.h"
 #include "include/i2caux_interface.h"
 
+enum aux_return_code_type;
+
 enum i2caux_transaction_operation {
 	I2CAUX_TRANSACTION_READ,
 	I2CAUX_TRANSACTION_WRITE
···
 		uint8_t *buffer,
 		uint8_t *reply_result,
 		uint32_t *sw_status);
-	enum aux_channel_operation_result (*get_channel_status)(
+	enum aux_return_code_type (*get_channel_status)(
 		struct aux_engine *engine,
 		uint8_t *returned_bytes);
 	bool (*is_engine_available)(struct aux_engine *engine);

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

···
 	DC_IRQ_SOURCE_DC4_VLINE1,
 	DC_IRQ_SOURCE_DC5_VLINE1,
 	DC_IRQ_SOURCE_DC6_VLINE1,
-
+	DC_IRQ_DMCUB_OUTBOX1,
 
 	DAL_IRQ_SOURCES_NUMBER
 };

drivers/gpu/drm/amd/display/dmub/dmub_srv.h

···
 	DMUB_WINDOW_TOTAL,
 };
 
+/* enum dmub_notification_type - dmub outbox notification identifier */
+enum dmub_notification_type {
+	DMUB_NOTIFICATION_NO_DATA = 0,
+	DMUB_NOTIFICATION_AUX_REPLY,
+	DMUB_NOTIFICATION_HPD,
+	DMUB_NOTIFICATION_HPD_IRQ,
+	DMUB_NOTIFICATION_MAX
+};
+
 /**
  * struct dmub_region - dmub hw memory region
  * @base: base address for region, must be 256 byte aligned
···
 
 	void (*set_inbox1_wptr)(struct dmub_srv *dmub, uint32_t wptr_offset);
 
+	void (*setup_out_mailbox)(struct dmub_srv *dmub,
+			      const struct dmub_region *outbox1);
+
+	uint32_t (*get_outbox1_wptr)(struct dmub_srv *dmub);
+
+	void (*set_outbox1_rptr)(struct dmub_srv *dmub, uint32_t rptr_offset);
+
 	uint32_t (*emul_get_inbox1_rptr)(struct dmub_srv *dmub);
 
 	void (*emul_set_inbox1_wptr)(struct dmub_srv *dmub, uint32_t wptr_offset);
···
 	struct dmub_srv_base_funcs funcs;
 	struct dmub_srv_hw_funcs hw_funcs;
 	struct dmub_rb inbox1_rb;
+	/**
+	 * outbox1_rb is accessed without locks (dal & dc)
+	 * and to be used only in dmub_srv_stat_get_notification()
+	 */
+	struct dmub_rb outbox1_rb;
 
 	bool sw_init;
 	bool hw_init;
···
 
 	/* Feature capabilities reported by fw */
 	struct dmub_feature_caps feature_caps;
+};
+
+/**
+ * struct dmub_notification - dmub notification data
+ * @type: dmub notification type
+ * @link_index: link index to identify aux connection
+ * @result: USB4 status returned from dmub
+ * @pending_notification: Indicates there are other pending notifications
+ * @aux_reply: aux reply
+ * @hpd_status: hpd status
+ */
+struct dmub_notification {
+	enum dmub_notification_type type;
+	uint8_t link_index;
+	uint8_t result;
+	bool pending_notification;
+	union {
+		struct aux_reply_data aux_reply;
+		enum dp_hpd_status hpd_status;
+	};
 };
 
 /**

drivers/gpu/drm/amd/display/dmub/dmub_srv_stat.h

···
+/*
+ * Copyright 2020 Advanced Micro Devices, Inc.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
+ * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+ * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ *
+ * Authors: AMD
+ *
+ */
+
+#ifndef _DMUB_SRV_STAT_H_
+#define _DMUB_SRV_STAT_H_
+
+/**
+ * DOC: DMUB_SRV STAT Interface
+ *
+ * These interfaces are called without acquiring DAL and DC locks.
+ * Hence, there is limitations on whese interfaces can access. Only
+ * variables exclusively defined for these interfaces can be modified.
+ */
+#include "dmub_srv.h"
+
+enum dmub_status dmub_srv_stat_get_notification(struct dmub_srv *dmub,
+						struct dmub_notification *notify);
+
+#endif /* _DMUB_SRV_STAT_H_ */

drivers/gpu/drm/amd/display/dmub/src/Makefile

···
 # OTHER DEALINGS IN THE SOFTWARE.
 #
 
-DMUB = dmub_srv.o dmub_reg.o dmub_dcn20.o dmub_dcn21.o
+DMUB = dmub_srv.o dmub_srv_stat.o dmub_reg.o dmub_dcn20.o dmub_dcn21.o
 DMUB += dmub_dcn30.o dmub_dcn301.o
 DMUB += dmub_dcn302.o
 

drivers/gpu/drm/amd/display/dmub/src/dmub_dcn20.c

···
 	REG_UPDATE(MMHUBBUB_SOFT_RESET, DMUIF_SOFT_RESET, 1);
 	REG_WRITE(DMCUB_INBOX1_RPTR, 0);
 	REG_WRITE(DMCUB_INBOX1_WPTR, 0);
+	REG_WRITE(DMCUB_OUTBOX1_RPTR, 0);
+	REG_WRITE(DMCUB_OUTBOX1_WPTR, 0);
 	REG_WRITE(DMCUB_SCRATCH0, 0);
 }
 
···
 void dmub_dcn20_set_inbox1_wptr(struct dmub_srv *dmub, uint32_t wptr_offset)
 {
 	REG_WRITE(DMCUB_INBOX1_WPTR, wptr_offset);
+}
+
+void dmub_dcn20_setup_out_mailbox(struct dmub_srv *dmub,
+			      const struct dmub_region *outbox1)
+{
+	/* New firmware can support CW4 for the outbox. */
+	if (dmub_dcn20_use_cached_inbox(dmub))
+		REG_WRITE(DMCUB_OUTBOX1_BASE_ADDRESS, outbox1->base);
+	else
+		REG_WRITE(DMCUB_OUTBOX1_BASE_ADDRESS, 0x80002000);
+
+	REG_WRITE(DMCUB_OUTBOX1_SIZE, outbox1->top - outbox1->base);
+}
+
+uint32_t dmub_dcn20_get_outbox1_wptr(struct dmub_srv *dmub)
+{
+	/**
+	 * outbox1 wptr register is accessed without locks (dal & dc)
+	 * and to be called only by dmub_srv_stat_get_notification()
+	 */
+	return REG_READ(DMCUB_OUTBOX1_WPTR);
+}
+
+void dmub_dcn20_set_outbox1_rptr(struct dmub_srv *dmub, uint32_t rptr_offset)
+{
+	/**
+	 * outbox1 rptr register is accessed without locks (dal & dc)
+	 * and to be called only by dmub_srv_stat_get_notification()
+	 */
+	REG_WRITE(DMCUB_OUTBOX1_RPTR, rptr_offset);
 }
 
 bool dmub_dcn20_is_hw_init(struct dmub_srv *dmub)

drivers/gpu/drm/amd/display/dmub/src/dmub_dcn20.h

···
 	DMUB_SR(DMCUB_INBOX1_SIZE) \
 	DMUB_SR(DMCUB_INBOX1_RPTR) \
 	DMUB_SR(DMCUB_INBOX1_WPTR) \
+	DMUB_SR(DMCUB_OUTBOX1_BASE_ADDRESS) \
+	DMUB_SR(DMCUB_OUTBOX1_SIZE) \
+	DMUB_SR(DMCUB_OUTBOX1_RPTR) \
+	DMUB_SR(DMCUB_OUTBOX1_WPTR) \
 	DMUB_SR(DMCUB_REGION3_CW0_OFFSET) \
 	DMUB_SR(DMCUB_REGION3_CW1_OFFSET) \
 	DMUB_SR(DMCUB_REGION3_CW2_OFFSET) \
···
 uint32_t dmub_dcn20_get_inbox1_rptr(struct dmub_srv *dmub);
 
 void dmub_dcn20_set_inbox1_wptr(struct dmub_srv *dmub, uint32_t wptr_offset);
+
+void dmub_dcn20_setup_out_mailbox(struct dmub_srv *dmub,
+			      const struct dmub_region *outbox1);
+
+uint32_t dmub_dcn20_get_outbox1_wptr(struct dmub_srv *dmub);
+
+void dmub_dcn20_set_outbox1_rptr(struct dmub_srv *dmub, uint32_t rptr_offset);
 
 bool dmub_dcn20_is_hw_init(struct dmub_srv *dmub);
 

drivers/gpu/drm/amd/display/dmub/src/dmub_srv.c

···
 /* Context size. */
 #define DMUB_CONTEXT_SIZE (512 * 1024)
 
-/* Mailbox size */
-#define DMUB_MAILBOX_SIZE (DMUB_RB_SIZE)
+/* Mailbox size : Ring buffers are required for both inbox and outbox */
+#define DMUB_MAILBOX_SIZE ((2 * DMUB_RB_SIZE))
 
 /* Default state size if meta is absent. */
 #define DMUB_FW_STATE_SIZE (64 * 1024)
···
 		funcs->get_fw_status = dmub_dcn20_get_fw_boot_status;
 		funcs->enable_dmub_boot_options = dmub_dcn20_enable_dmub_boot_options;
 		funcs->skip_dmub_panel_power_sequence = dmub_dcn20_skip_dmub_panel_power_sequence;
+
+		// Out mailbox register access functions for RN and above
+		funcs->setup_out_mailbox = dmub_dcn20_setup_out_mailbox;
+		funcs->get_outbox1_wptr = dmub_dcn20_get_outbox1_wptr;
+		funcs->set_outbox1_rptr = dmub_dcn20_set_outbox1_rptr;
 
 		if (asic == DMUB_ASIC_DCN21) {
 			dmub->regs = &dmub_srv_dcn21_regs;
···
 
 	struct dmub_rb_init_params rb_params;
 	struct dmub_window cw0, cw1, cw2, cw3, cw4, cw5, cw6;
-	struct dmub_region inbox1;
+	struct dmub_region inbox1, outbox1;
 
 	if (!dmub->sw_init)
 		return DMUB_STATUS_INVALID;
···
 		cw4.region.base = DMUB_CW4_BASE;
 		cw4.region.top = cw4.region.base + mail_fb->size;
 
+		/**
+		 * Doubled the mailbox region to accomodate inbox and outbox.
+		 * Note: Currently, currently total mailbox size is 16KB. It is split
+		 * equally into 8KB between inbox and outbox. If this config is
+		 * changed, then uncached base address configuration of outbox1
+		 * has to be updated in funcs->setup_out_mailbox.
+		 */
 		inbox1.base = cw4.region.base;
-		inbox1.top = cw4.region.top;
+		inbox1.top = cw4.region.base + DMUB_RB_SIZE;
+		outbox1.base = inbox1.top;
+		outbox1.top = cw4.region.top;
 
 		cw5.offset.quad_part = tracebuff_fb->gpu_addr;
 		cw5.region.base = DMUB_CW5_BASE;
···
 
 		if (dmub->hw_funcs.setup_mailbox)
 			dmub->hw_funcs.setup_mailbox(dmub, &inbox1);
+		if (dmub->hw_funcs.setup_out_mailbox)
+			dmub->hw_funcs.setup_out_mailbox(dmub, &outbox1);
 	}
 
 	if (mail_fb) {
···
 		rb_params.capacity = DMUB_RB_SIZE;
 
 		dmub_rb_init(&dmub->inbox1_rb, &rb_params);
+
+		// Initialize outbox1 ring buffer
+		rb_params.ctx = dmub;
+		rb_params.base_address = (void *) ((uint64_t) (mail_fb->cpu_addr) + DMUB_RB_SIZE);
+		rb_params.capacity = DMUB_RB_SIZE;
+		dmub_rb_init(&dmub->outbox1_rb, &rb_params);
+
 	}
 
 	if (dmub->hw_funcs.reset_release)

drivers/gpu/drm/amd/display/dmub/src/dmub_srv_stat.c

···
+/*
+ * Copyright 2019 Advanced Micro Devices, Inc.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
+ * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+ * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ *
+ * Authors: AMD
+ *
+ */
+
+#include "dmub/dmub_srv_stat.h"
+#include "dmub/inc/dmub_cmd.h"
+
+/**
+ * DOC: DMUB_SRV STAT Interface
+ *
+ * These interfaces are called without acquiring DAL and DC locks.
+ * Hence, there is limitations on whese interfaces can access. Only
+ * variables exclusively defined for these interfaces can be modified.
+ */
+
+/**
+ *****************************************************************************
+ *  Function: dmub_srv_stat_get_notification
+ *
+ *  @brief
+ *		Retrieves a dmub outbox notification, set up dmub notification
+ *		structure with message information. Also a pending bit if queue
+ *		is having more notifications
+ *
+ *  @param [in] dmub: dmub srv structure
+ *  @param [out] pnotify: dmub notification structure to be filled up
+ *
+ *  @return
+ *     dmub_status
+ *****************************************************************************
+ */
+enum dmub_status dmub_srv_stat_get_notification(struct dmub_srv *dmub,
+						struct dmub_notification *notify)
+{
+	/**
+	 * This function is called without dal and dc locks, so
+	 * we shall not modify any dmub variables, only dmub->outbox1_rb
+	 * is exempted as it is exclusively accessed by this function
+	 */
+	union dmub_rb_out_cmd cmd = {0};
+
+	if (!dmub->hw_init) {
+		notify->type = DMUB_NOTIFICATION_NO_DATA;
+		notify->pending_notification = false;
+		return DMUB_STATUS_INVALID;
+	}
+
+	/* Get write pointer which is updated by dmub */
+	dmub->outbox1_rb.wrpt = dmub->hw_funcs.get_outbox1_wptr(dmub);
+
+	if (!dmub_rb_out_front(&dmub->outbox1_rb, &cmd)) {
+		notify->type = DMUB_NOTIFICATION_NO_DATA;
+		notify->pending_notification = false;
+		return DMUB_STATUS_OK;
+	}
+
+	switch (cmd.cmd_common.header.type) {
+	case DMUB_OUT_CMD__DP_AUX_REPLY:
+		notify->type = DMUB_NOTIFICATION_AUX_REPLY;
+		notify->link_index = cmd.dp_aux_reply.control.instance;
+		notify->result = cmd.dp_aux_reply.control.result;
+		dmub_memcpy((void *)&notify->aux_reply,
+			(void *)&cmd.dp_aux_reply.reply_data, sizeof(struct aux_reply_data));
+		break;
+	default:
+		notify->type = DMUB_NOTIFICATION_NO_DATA;
+		break;
+	}
+
+	/* Pop outbox1 ringbuffer and update read pointer */
+	dmub_rb_pop_front(&dmub->outbox1_rb);
+	dmub->hw_funcs.set_outbox1_rptr(dmub, dmub->outbox1_rb.rptr);
+
+	/**
+	 * Notify dc whether dmub has a pending outbox message,
+	 * this is to avoid one more call to dmub_srv_stat_get_notification
+	 */
+	if (dmub_rb_empty(&dmub->outbox1_rb))
+		notify->pending_notification = false;
+	else
+		notify->pending_notification = true;
+
+	return DMUB_STATUS_OK;
+}