ALSA: ump: Transmit RPN/NRPN message at each MSB/LSB data reception

The UMP 1.1 spec says that an RPN/NRPN should be sent when one of the
following occurs:
* a CC 38 is received
* a subsequent CC 6 is received
* a CC 98, 99, 100, and 101 is received, indicating the last RPN/NRPN
  message has ended and a new one has started

That said, we should send a partial data even if it's not fully
filled.  Let's change the UMP conversion helper code to follow that
rule.

Link: https://patch.msgid.link/20240731130528.12600-2-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/include/sound/ump_convert.h b/include/sound/ump_convert.h
index 28c364c63245d035004d5b6210a4181dbfc135f6..d099ae27f8491afbbcc65dea5f22149d448b7a92 100644 (file)
--- a/include/sound/ump_convert.h
+++ b/include/sound/ump_convert.h
@@ -13,6 +13,7 @@ struct ump_cvt_to_ump_bank {
        unsigned char cc_nrpn_msb, cc_nrpn_lsb;
        unsigned char cc_data_msb, cc_data_lsb;
        unsigned char cc_bank_msb, cc_bank_lsb;
+       bool cc_data_msb_set, cc_data_lsb_set;
 };
 
 /* context for converting from MIDI1 byte stream to UMP packet */

diff --git a/sound/core/ump_convert.c b/sound/core/ump_convert.c
index f67c44c83fde445258c59f34897b73a913c17cf1..5d1b85e7ac165a61b8bc7fa87dc93cf684a9e09b 100644 (file)
--- a/sound/core/ump_convert.c
+++ b/sound/core/ump_convert.c
@@ -287,25 +287,37 @@ static int cvt_legacy_system_to_ump(struct ump_cvt_to_ump *cvt,
        return 4;
 }
 
-static void fill_rpn(struct ump_cvt_to_ump_bank *cc,
-                    union snd_ump_midi2_msg *midi2)
+static int fill_rpn(struct ump_cvt_to_ump_bank *cc,
+                   union snd_ump_midi2_msg *midi2,
+                   bool flush)
 {
+       if (!(cc->cc_data_lsb_set || cc->cc_data_msb_set))
+               return 0; // skip
+       /* when not flushing, wait for complete data set */
+       if (!flush && (!cc->cc_data_lsb_set || !cc->cc_data_msb_set))
+               return 0; // skip
+
        if (cc->rpn_set) {
                midi2->rpn.status = UMP_MSG_STATUS_RPN;
                midi2->rpn.bank = cc->cc_rpn_msb;
                midi2->rpn.index = cc->cc_rpn_lsb;
-               cc->rpn_set = 0;
-               cc->cc_rpn_msb = cc->cc_rpn_lsb = 0;
-       } else {
+       } else if (cc->nrpn_set) {
                midi2->rpn.status = UMP_MSG_STATUS_NRPN;
                midi2->rpn.bank = cc->cc_nrpn_msb;
                midi2->rpn.index = cc->cc_nrpn_lsb;
-               cc->nrpn_set = 0;
-               cc->cc_nrpn_msb = cc->cc_nrpn_lsb = 0;
+       } else {
+               return 0; // skip
        }
+
        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;
+       return 1;
 }
 
 /* convert to a MIDI 1.0 Channel Voice message */
@@ -318,6 +330,7 @@ static int cvt_legacy_cmd_to_ump(struct ump_cvt_to_ump *cvt,
        struct ump_cvt_to_ump_bank *cc;
        union snd_ump_midi2_msg *midi2 = (union snd_ump_midi2_msg *)data;
        unsigned char status, channel;
+       int ret;
 
        BUILD_BUG_ON(sizeof(union snd_ump_midi1_msg) != 4);
        BUILD_BUG_ON(sizeof(union snd_ump_midi2_msg) != 8);
@@ -358,24 +371,29 @@ static int cvt_legacy_cmd_to_ump(struct ump_cvt_to_ump *cvt,
        case UMP_MSG_STATUS_CC:
                switch (buf[1]) {
                case UMP_CC_RPN_MSB:
+                       ret = fill_rpn(cc, midi2, true);
                        cc->rpn_set = 1;
                        cc->cc_rpn_msb = buf[2];
-                       return 0; // skip
+                       return ret;
                case UMP_CC_RPN_LSB:
+                       ret = fill_rpn(cc, midi2, true);
                        cc->rpn_set = 1;
                        cc->cc_rpn_lsb = buf[2];
-                       return 0; // skip
+                       return ret;
                case UMP_CC_NRPN_MSB:
+                       ret = fill_rpn(cc, midi2, true);
                        cc->nrpn_set = 1;
                        cc->cc_nrpn_msb = buf[2];
-                       return 0; // skip
+                       return ret;
                case UMP_CC_NRPN_LSB:
+                       ret = fill_rpn(cc, midi2, true);
                        cc->nrpn_set = 1;
                        cc->cc_nrpn_lsb = buf[2];
-                       return 0; // skip
+                       return ret;
                case UMP_CC_DATA:
+                       cc->cc_data_msb_set = 1;
                        cc->cc_data_msb = buf[2];
-                       return 0; // skip
+                       return fill_rpn(cc, midi2, false);
                case UMP_CC_BANK_SELECT:
                        cc->bank_set = 1;
                        cc->cc_bank_msb = buf[2];
@@ -385,12 +403,9 @@ static int cvt_legacy_cmd_to_ump(struct ump_cvt_to_ump *cvt,
                        cc->cc_bank_lsb = buf[2];
                        return 0; // skip
                case UMP_CC_DATA_LSB:
+                       cc->cc_data_lsb_set = 1;
                        cc->cc_data_lsb = buf[2];
-                       if (cc->rpn_set || cc->nrpn_set)
-                               fill_rpn(cc, midi2);
-                       else
-                               return 0; // skip
-                       break;
+                       return fill_rpn(cc, midi2, false);
                default:
                        midi2->cc.index = buf[1];
                        midi2->cc.data = upscale_7_to_32bit(buf[2]);