ALSA: seq: ump: Explicitly reset RPN with Null RPN

RPN with 127:127 is treated as a Null RPN, just to reset the
parameters, and it's not translated to MIDI2.  Although the current
code can work as is in most cases, better to implement the RPN reset
explicitly for Null message.

Link: https://patch.msgid.link/20240731130528.12600-6-tiwai@suse.deSigned-off-by: Takashi Iwai <tiwai@suse.de>

sound/core/seq/seq_ump_convert.c

@@ -789,6 +789,15 @@ static int paf_ev_to_ump_midi2(const struct snd_seq_event *event,
 	return 1;
 }
 
+static void reset_rpn(struct ump_cvt_to_ump_bank *cc)
+{
+	cc->rpn_set = 0;
+	cc->nrpn_set = 0;
+	cc->cc_rpn_msb = cc->cc_rpn_lsb = 0;
+	cc->cc_data_msb = cc->cc_data_lsb = 0;
+	cc->cc_data_msb_set = cc->cc_data_lsb_set = 0;
+}
+
 /* set up the MIDI2 RPN/NRPN packet data from the parsed info */
 static int fill_rpn(struct ump_cvt_to_ump_bank *cc,
 		    union snd_ump_midi2_msg *data,
@@ -817,11 +826,7 @@ static int fill_rpn(struct ump_cvt_to_ump_bank *cc,
 					     cc->cc_data_lsb);
 	data->rpn.channel = channel;
 
-	cc->rpn_set = 0;
-	cc->nrpn_set = 0;
-	cc->cc_rpn_msb = cc->cc_rpn_lsb = 0;
-	cc->cc_data_msb = cc->cc_data_lsb = 0;
-	cc->cc_data_msb_set = cc->cc_data_lsb_set = 0;
+	reset_rpn(cc);
 	return 1;
 }
 
@@ -843,11 +848,15 @@ static int cc_ev_to_ump_midi2(const struct snd_seq_event *event,
 		ret = fill_rpn(cc, data, channel, true);
 		cc->rpn_set = 1;
 		cc->cc_rpn_msb = val;
+		if (cc->cc_rpn_msb == 0x7f && cc->cc_rpn_lsb == 0x7f)
+			reset_rpn(cc);
 		return ret;
 	case UMP_CC_RPN_LSB:
 		ret = fill_rpn(cc, data, channel, true);
 		cc->rpn_set = 1;
 		cc->cc_rpn_lsb = val;
+		if (cc->cc_rpn_msb == 0x7f && cc->cc_rpn_lsb == 0x7f)
+			reset_rpn(cc);
 		return ret;
 	case UMP_CC_NRPN_MSB:
 		ret = fill_rpn(cc, data, channel, true);
@@ -961,6 +970,8 @@ static int ctrl14_ev_to_ump_midi2(const struct snd_seq_event *event,
 		cc->cc_rpn_msb = msb;
 		cc->cc_rpn_lsb = lsb;
 		cc->rpn_set = 1;
+		if (cc->cc_rpn_msb == 0x7f && cc->cc_rpn_lsb == 0x7f)
+			reset_rpn(cc);
 		return ret;
 	case UMP_CC_NRPN_MSB:
 	case UMP_CC_NRPN_LSB: