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ALSA: usx2y: Drain pending US-428 pipe-4 output commands

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The US-428 pipe-4 output path submits at most one pending p4out
entry from the shared-memory ring per input interrupt. If userspace
queues more than one command before the interrupt handler runs, later
commands remain pending until later input interrupts, even when async
pipe-4 URBs are available.

Drain pending entries while idle async URBs are available. Copy each
command into the existing per-URB async buffer before submission, so the
submitted transfer does not depend on a userspace-mapped ring slot
remaining unchanged after p4out_sent is advanced.

Also update p4out_sent only after usb_submit_urb() succeeds, so a
failed submission is not reported as sent.

This keeps the shared-memory ABI unchanged and fixes only the local
queue-draining behavior.

Signed-off-by: Cássio Gabriel <cassiogabrielcontato@gmail.com>
Link: https://patch.msgid.link/20260519-alsa-usx2y-p4out-drain-v1-1-8f0a4550bae2@gmail.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Cássio Gabriel 2026-05-19 00:20:41 -03:00 committed by Takashi Iwai
parent 0c09413bde
commit 18977c0dd7
1 changed files with 23 additions and 16 deletions
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39
sound/usb/usx2y/usbusx2y.c
View File

@ -180,7 +180,7 @@ static void i_usx2y_in04_int(struct urb *urb)
struct usx2ydev *usx2y = urb->context;
struct us428ctls_sharedmem *us428ctls = usx2y->us428ctls_sharedmem;
struct us428_p4out *p4out;
int i, j, n, diff, send;
int i, j, n, diff, send, len;
usx2y->in04_int_calls++;
@ -222,24 +222,31 @@ static void i_usx2y_in04_int(struct urb *urb)
} while (!err && usx2y->us04->submitted < usx2y->us04->len);
}
} else {
if (us428ctls && us428ctls->p4out_last >= 0 && us428ctls->p4out_last < N_US428_P4OUT_BUFS) {
if (us428ctls->p4out_last != us428ctls->p4out_sent) {
send = us428ctls->p4out_sent + 1;
if (send >= N_US428_P4OUT_BUFS)
send = 0;
for (j = 0; j < URBS_ASYNC_SEQ && !err; ++j) {
if (!usx2y->as04.urb[j]->status) {
p4out = us428ctls->p4out + send; // FIXME if more than 1 p4out is new, 1 gets lost.
usb_fill_bulk_urb(usx2y->as04.urb[j], usx2y->dev,
usb_sndbulkpipe(usx2y->dev, 0x04), &p4out->val.vol,
p4out->type == ELT_LIGHT ? sizeof(struct us428_lights) : 5,
i_usx2y_out04_int, usx2y);
err = usb_submit_urb(usx2y->as04.urb[j], GFP_ATOMIC);
while (us428ctls &&
us428ctls->p4out_last >= 0 &&
us428ctls->p4out_last < N_US428_P4OUT_BUFS &&
us428ctls->p4out_last != us428ctls->p4out_sent) {
for (j = 0; j < URBS_ASYNC_SEQ && !err; ++j) {
if (!usx2y->as04.urb[j]->status) {
send = us428ctls->p4out_sent + 1;
if (send >= N_US428_P4OUT_BUFS)
send = 0;
p4out = us428ctls->p4out + send;
len = p4out->type == ELT_LIGHT ?
sizeof(struct us428_lights) : 5;
memcpy(usx2y->as04.urb[j]->transfer_buffer,
&p4out->val.vol, len);
usx2y->as04.urb[j]->transfer_buffer_length = len;
err = usb_submit_urb(usx2y->as04.urb[j], GFP_ATOMIC);
if (!err)
us428ctls->p4out_sent = send;
break;
}
break;
}
}
if (j >= URBS_ASYNC_SEQ || err)
break;
}
}