[PATCH AUTOSEL 6.6 10/15] ALSA: ump: Explicitly reset RPN with Null RPN

[Sasha Levin <sashal@kernel.org>]

From: Takashi Iwai <tiwai@suse.de>

[ Upstream commit 50a6dd19dca9446475f023eaa652016bfe5b1cbe ]

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/20240731130528.12600-3-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 sound/core/ump_convert.c | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/sound/core/ump_convert.c b/sound/core/ump_convert.c
index 5d1b85e7ac165..0fe13d0316568 100644
--- a/sound/core/ump_convert.c
+++ b/sound/core/ump_convert.c
@@ -287,6 +287,15 @@ static int cvt_legacy_system_to_ump(struct ump_cvt_to_ump *cvt,
 	return 4;
 }
 
+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;
+}
+
 static int fill_rpn(struct ump_cvt_to_ump_bank *cc,
 		    union snd_ump_midi2_msg *midi2,
 		    bool flush)
@@ -312,11 +321,7 @@ static int fill_rpn(struct ump_cvt_to_ump_bank *cc,
 	midi2->rpn.data = upscale_14_to_32bit((cc->cc_data_msb << 7) |
 					      cc->cc_data_lsb);
 
-	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;
 }
 
@@ -374,11 +379,15 @@ static int cvt_legacy_cmd_to_ump(struct ump_cvt_to_ump *cvt,
 			ret = fill_rpn(cc, midi2, true);
 			cc->rpn_set = 1;
 			cc->cc_rpn_msb = buf[2];
+			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, midi2, true);
 			cc->rpn_set = 1;
 			cc->cc_rpn_lsb = buf[2];
+			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, midi2, true);
-- 
2.43.0