Re: missing sound on kernel-5.15

[Takashi Iwai <tiwai@suse.de>]

On Mon, 29 Aug 2022 10:50:58 +0200,
chihhao chen wrote:
> 
> Hi Takashi,
> 
> Yes.
> 
> To issue SAMPLING_FREQ_CONTROL USB request two times is root cause of
> this issue.

Hm, is it a UAC1 device?  Such a device should work with multiple
SAMPLING_FREQ_CONTROL invocations, but some device might be not
tolerant or buggy...  The multiple init_sample_rate() invocations may
happen with the older kernel under certain situations, so maybe we
need a different fix.

How about the patch like below?


thanks,

Takashi

---
diff --git a/sound/usb/card.h b/sound/usb/card.h
index ca75f2206170..507cd62f0ff8 100644
--- a/sound/usb/card.h
+++ b/sound/usb/card.h
@@ -134,6 +134,7 @@ struct snd_usb_endpoint {
 	/* for hw constraints */
 	const struct audioformat *cur_audiofmt;
 	unsigned int cur_rate;
+	unsigned int cur_rate_setup;
 	snd_pcm_format_t cur_format;
 	unsigned int cur_channels;
 	unsigned int cur_frame_bytes;
diff --git a/sound/usb/endpoint.c b/sound/usb/endpoint.c
index 0d7b73bf7945..1a5a9bc98a96 100644
--- a/sound/usb/endpoint.c
+++ b/sound/usb/endpoint.c
@@ -806,6 +806,7 @@ snd_usb_endpoint_open(struct snd_usb_audio *chip,
 		ep->cur_audiofmt = fp;
 		ep->cur_channels = fp->channels;
 		ep->cur_rate = params_rate(params);
+		ep->cur_rate_setup = 0;
 		ep->cur_format = params_format(params);
 		ep->cur_frame_bytes = snd_pcm_format_physical_width(ep->cur_format) *
 			ep->cur_channels / 8;
@@ -928,6 +929,7 @@ void snd_usb_endpoint_close(struct snd_usb_audio *chip,
 		ep->altsetting = 0;
 		ep->cur_audiofmt = NULL;
 		ep->cur_rate = 0;
+		ep->cur_rate_setup = 0;
 		ep->iface_ref = NULL;
 		ep->clock_ref = NULL;
 		usb_audio_dbg(chip, "EP 0x%x closed\n", ep->ep_num);
@@ -1356,6 +1358,9 @@ static int init_sample_rate(struct snd_usb_audio *chip,
 	struct snd_usb_clock_ref *clock = ep->clock_ref;
 	int err;
 
+	if (ep->cur_rate == ep->cur_rate_setup)
+		return 0;
+
 	if (clock) {
 		if (atomic_read(&clock->locked))
 			return 0;
@@ -1374,6 +1379,7 @@ static int init_sample_rate(struct snd_usb_audio *chip,
 
 	if (clock)
 		clock->rate = ep->cur_rate;
+	ep->cur_rate_setup = ep->cur_rate;
 	return 0;
 }