drm/amd/pm: Ignore initial value in smu response register

Why:
If the reg mmMP1_SMN_C2PMSG_90 is being written to during amdgpu driver
load or driver unload, subsequent amdgpu driver load will fail at
smu_hw_init. The default of mmMP1_SMN_C2PMSG_90 register at a clean
environment is 0x1 and if value differs from expected, amdgpu driver
load will fail.

How to fix:
Ignore the initial value in smu response register before the first smu
message is sent,if smc in SMU_FW_INIT state, just proceed further to
send the message. If register holds an unexpected value after smu message
was sent set, smc_state to SMU_FW_HANG state and no further smu messages
will be sent.

v2:
Set SMU_FW_INIT state at the start of smu hw_init/resume.
Check smc_fw_state before sending smu message if in hang state skip
sending message.
Set SMU_FW_HANG only in case unexpected value is detected
Signed-off-by: Danijel Slivka <danijel.slivka@amd.com>
Reviewed-by: Kenneth Feng <kenneth.feng@amd.com>
Reviewed-by: Lijo Lazar <lijo.lazar@amd.com>
Reviewed-by: Asad Kamal <asad.kamal@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/pm/swsmu/amdgpu_smu.c

@@ -1755,6 +1755,8 @@ static int smu_start_smc_engine(struct smu_context *smu)
 	struct amdgpu_device *adev = smu->adev;
 	int ret = 0;
 
+	smu->smc_fw_state = SMU_FW_INIT;
+
 	if (adev->firmware.load_type != AMDGPU_FW_LOAD_PSP) {
 		if (amdgpu_ip_version(adev, MP1_HWIP, 0) < IP_VERSION(11, 0, 0)) {
 			if (smu->ppt_funcs->load_microcode) {

drivers/gpu/drm/amd/pm/swsmu/inc/amdgpu_smu.h

@@ -495,6 +495,12 @@ struct stb_context {
 	spinlock_t lock;
 };
 
+enum smu_fw_status {
+	SMU_FW_INIT = 0,
+	SMU_FW_RUNTIME,
+	SMU_FW_HANG,
+};
+
 #define WORKLOAD_POLICY_MAX 7
 
 /*
@@ -562,6 +568,7 @@ struct smu_context {
 	uint32_t smc_fw_if_version;
 	uint32_t smc_fw_version;
 	uint32_t smc_fw_caps;
+	uint8_t smc_fw_state;
 
 	bool uploading_custom_pp_table;
 	bool dc_controlled_by_gpio;

drivers/gpu/drm/amd/pm/swsmu/smu_cmn.c

@@ -315,11 +315,21 @@ int smu_cmn_send_msg_without_waiting(struct smu_context *smu,
 	if (adev->no_hw_access)
 		return 0;
 
-	reg = __smu_cmn_poll_stat(smu);
-	res = __smu_cmn_reg2errno(smu, reg);
-	if (reg == SMU_RESP_NONE ||
-	    res == -EREMOTEIO)
+	if (smu->smc_fw_state == SMU_FW_HANG) {
+		dev_err(adev->dev, "SMU is in hanged state, failed to send smu message!\n");
+		res = -EREMOTEIO;
 		goto Out;
+	}
+
+	if (smu->smc_fw_state == SMU_FW_INIT) {
+		smu->smc_fw_state = SMU_FW_RUNTIME;
+	} else {
+		reg = __smu_cmn_poll_stat(smu);
+		res = __smu_cmn_reg2errno(smu, reg);
+		if (reg == SMU_RESP_NONE || res == -EREMOTEIO)
+			goto Out;
+	}
+
 	__smu_cmn_send_msg(smu, msg_index, param);
 	res = 0;
 Out:
@@ -350,6 +360,9 @@ int smu_cmn_wait_for_response(struct smu_context *smu)
 	reg = __smu_cmn_poll_stat(smu);
 	res = __smu_cmn_reg2errno(smu, reg);
 
+	if (res == -EREMOTEIO)
+		smu->smc_fw_state = SMU_FW_HANG;
+
 	if (unlikely(smu->adev->pm.smu_debug_mask & SMU_DEBUG_HALT_ON_ERROR) &&
 	    res && (res != -ETIME)) {
 		amdgpu_device_halt(smu->adev);
@@ -418,6 +431,16 @@ int smu_cmn_send_smc_msg_with_param(struct smu_context *smu,
 			goto Out;
 	}
 
+	if (smu->smc_fw_state == SMU_FW_HANG) {
+		dev_err(adev->dev, "SMU is in hanged state, failed to send smu message!\n");
+		res = -EREMOTEIO;
+		goto Out;
+	} else if (smu->smc_fw_state == SMU_FW_INIT) {
+		/* Ignore initial smu response register value */
+		poll = false;
+		smu->smc_fw_state = SMU_FW_RUNTIME;
+	}
+
 	if (poll) {
 		reg = __smu_cmn_poll_stat(smu);
 		res = __smu_cmn_reg2errno(smu, reg);
@@ -429,8 +452,11 @@ int smu_cmn_send_smc_msg_with_param(struct smu_context *smu,
 	__smu_cmn_send_msg(smu, (uint16_t) index, param);
 	reg = __smu_cmn_poll_stat(smu);
 	res = __smu_cmn_reg2errno(smu, reg);
-	if (res != 0)
+	if (res != 0) {
+		if (res == -EREMOTEIO)
+			smu->smc_fw_state = SMU_FW_HANG;
 		__smu_cmn_reg_print_error(smu, reg, index, param, msg);
+	}
 	if (read_arg) {
 		smu_cmn_read_arg(smu, read_arg);
 		dev_dbg(adev->dev, "smu send message: %s(%d) param: 0x%08x, resp: 0x%08x,\