i3c: master: Move bus_init error suppression

Prepare to fix improper Mx positive error propagation in later commits
by handling Mx error codes where the i3c_ccc_cmd command is allocated.
The CCC DISEC to broadcast address is invoked with
i3c_master_enec_disec_locked() and yields error I3C_ERROR_M2 if there
are no devices active on the bus. This is expected at the bus
initialization stage, where it is not known yet that there are no active
devices on the bus. Add bool suppress_m2 argument to
i3c_master_enec_disec_locked() and update the call site at
i3c_master_bus_init() with the exact corner case to not require
propagating positive Mx error codes. Other call site should not suppress
the error code, for example, if a driver requests to peripheral to
disable events and the transfer is not acknowledged, this is an error
and should not proceed.

Reviewed-by: Frank Li <Frank.Li@nxp.com>
Reviewed-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Jorge Marques <jorge.marques@analog.com>
Link: https://patch.msgid.link/20260323-ad4062-positive-error-fix-v3-3-30bdc68004be@analog.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

Author: gastmaier

drivers/i3c/master.c

@@ -1086,7 +1086,8 @@ int i3c_master_entdaa_locked(struct i3c_master_controller *master)
 EXPORT_SYMBOL_GPL(i3c_master_entdaa_locked);
 
 static int i3c_master_enec_disec_locked(struct i3c_master_controller *master,
-					u8 addr, bool enable, u8 evts)
+					u8 addr, bool enable, u8 evts,
+					bool suppress_m2)
 {
 	struct i3c_ccc_events *events;
 	struct i3c_ccc_cmd_dest dest;
@@ -1106,6 +1107,9 @@ static int i3c_master_enec_disec_locked(struct i3c_master_controller *master,
 	ret = i3c_master_send_ccc_cmd_locked(master, &cmd);
 	i3c_ccc_cmd_dest_cleanup(&dest);
 
+	if (suppress_m2 && ret && cmd.err == I3C_ERROR_M2)
+		ret = 0;
+
 	return ret;
 }
 
@@ -1126,7 +1130,7 @@ static int i3c_master_enec_disec_locked(struct i3c_master_controller *master,
 int i3c_master_disec_locked(struct i3c_master_controller *master, u8 addr,
 			    u8 evts)
 {
-	return i3c_master_enec_disec_locked(master, addr, false, evts);
+	return i3c_master_enec_disec_locked(master, addr, false, evts, false);
 }
 EXPORT_SYMBOL_GPL(i3c_master_disec_locked);
 
@@ -1147,7 +1151,7 @@ EXPORT_SYMBOL_GPL(i3c_master_disec_locked);
 int i3c_master_enec_locked(struct i3c_master_controller *master, u8 addr,
 			   u8 evts)
 {
-	return i3c_master_enec_disec_locked(master, addr, true, evts);
+	return i3c_master_enec_disec_locked(master, addr, true, evts, false);
 }
 EXPORT_SYMBOL_GPL(i3c_master_enec_locked);
 
@@ -2134,11 +2138,14 @@ static int i3c_master_bus_init(struct i3c_master_controller *master)
 			goto err_bus_cleanup;
 	}
 
-	/* Disable all slave events before starting DAA. */
-	ret = i3c_master_disec_locked(master, I3C_BROADCAST_ADDR,
-				      I3C_CCC_EVENT_SIR | I3C_CCC_EVENT_MR |
-				      I3C_CCC_EVENT_HJ);
-	if (ret && ret != I3C_ERROR_M2)
+	/*
+	 * Disable all slave events before starting DAA. When no active device
+	 * is on the bus, returns Mx error code M2, this error is ignored.
+	 */
+	ret = i3c_master_enec_disec_locked(master, I3C_BROADCAST_ADDR, false,
+					   I3C_CCC_EVENT_SIR | I3C_CCC_EVENT_MR |
+					   I3C_CCC_EVENT_HJ, true);
+	if (ret)
 		goto err_bus_cleanup;
 
 	/*