ALSA: ump: Add info flag bit for static blocks

UMP v1.1 spec allows to inform whether the function blocks are static
and not dynamically updated.  Add a new flag bit to
snd_ump_endpoint_info to reflect that attribute, too.

The flag is set when a USB MIDI device is still in the old MIDI 2.0
without UMP 1.1 support.  Then the driver falls back to GTBs, and they
are supposed to be static-only.

Link: https://lore.kernel.org/r/20230612081054.17200-10-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>

include/uapi/sound/asound.h

@@ -780,6 +780,9 @@ struct snd_rawmidi_status {
 };
 #endif
 
+/* UMP EP info flags */
+#define SNDRV_UMP_EP_INFO_STATIC_BLOCKS		0x01
+
 /* UMP EP Protocol / JRTS capability bits */
 #define SNDRV_UMP_EP_INFO_PROTO_MIDI_MASK	0x0300
 #define SNDRV_UMP_EP_INFO_PROTO_MIDI1		0x0100 /* MIDI 1.0 */

sound/core/ump.c

@@ -490,6 +490,8 @@ static void snd_ump_proc_read(struct snd_info_entry *entry,
 			    ump->info.sw_revision[2],
 			    ump->info.sw_revision[3]);
 	}
+	snd_iprintf(buffer, "Static Blocks: %s\n",
+		    (ump->info.flags & SNDRV_UMP_EP_INFO_STATIC_BLOCKS) ? "Yes" : "No");
 	snd_iprintf(buffer, "Num Blocks: %d\n\n", ump->info.num_blocks);
 
 	list_for_each_entry(fb, &ump->block_list, list) {
@@ -608,6 +610,9 @@ static int ump_handle_ep_info_msg(struct snd_ump_endpoint *ump,
 		ump->info.num_blocks = 1;
 	}
 
+	if (buf->ep_info.static_function_block)
+		ump->info.flags |= SNDRV_UMP_EP_INFO_STATIC_BLOCKS;
+
 	ump->info.protocol_caps = (buf->ep_info.protocol << 8) |
 		buf->ep_info.jrts;
 
@@ -708,6 +713,12 @@ static bool is_fb_info_updated(struct snd_ump_endpoint *ump,
 {
 	char tmpbuf[offsetof(struct snd_ump_block_info, name)];
 
+	if (ump->info.flags & SNDRV_UMP_EP_INFO_STATIC_BLOCKS) {
+		ump_info(ump, "Skipping static FB info update (blk#%d)\n",
+			 fb->info.block_id);
+		return 0;
+	}
+
 	memcpy(tmpbuf, &fb->info, sizeof(tmpbuf));
 	fill_fb_info(ump, (struct snd_ump_block_info *)tmpbuf, buf);
 	return memcmp(&fb->info, tmpbuf, sizeof(tmpbuf)) != 0;

sound/usb/midi2.c

@@ -888,6 +888,8 @@ static int create_blocks_from_gtb(struct snd_usb_midi2_interface *umidi)
 		/* Blocks have been already created? */
 		if (rmidi->ump_parsed || rmidi->ump->info.num_blocks)
 			continue;
+		/* GTB is static-only */
+		rmidi->ump->info.flags |= SNDRV_UMP_EP_INFO_STATIC_BLOCKS;
 		/* loop over GTBs */
 		for (dir = 0; dir < 2; dir++) {
 			if (!rmidi->eps[dir])