ALSA: usb-audio: Limit retrying sample rate reads (57dd5414) · Commits · 戴 / test

There are many USB audio devices with buggy firmware that don't react with the sample rate reading properly. This often results in the flood of error messages and slowing down the operation. The sample rate read back is basically only for confirming the sample rate setup, and it's not critically important. As a compromise, in this patch, we stop the sample rate read back once when the device gives errors more than tolerance (twice, as of now). This should improve most of error cases while we still can catch the firmware bugginess. Signed-off-by:

Takashi Iwai <tiwai@suse.de>

sound/usb/clock.c

+4 −0

Original line number	Diff line number	Diff line
		@@ -309,6 +309,9 @@ static int set_sample_rate_v1(struct snd_usb_audio *chip, int iface,
		* support reading */
		if (snd_usb_get_sample_rate_quirk(chip))
		return 0;
		/* the firmware is likely buggy, don't repeat to fail too many times */
		if (chip->sample_rate_read_error > 2)
		return 0;

		if ((err = snd_usb_ctl_msg(dev, usb_rcvctrlpipe(dev, 0), UAC_GET_CUR,
		USB_TYPE_CLASS \| USB_RECIP_ENDPOINT \| USB_DIR_IN,
		@@ -316,6 +319,7 @@ static int set_sample_rate_v1(struct snd_usb_audio *chip, int iface,
		data, sizeof(data))) < 0) {
		dev_err(&dev->dev, "%d:%d: cannot get freq at ep %#x\n",
		iface, fmt->altsetting, ep);
		chip->sample_rate_read_error++;
		return 0; /* some devices don't support reading */
		}

sound/usb/usbaudio.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -50,6 +50,7 @@ struct snd_usb_audio {

		int num_interfaces;
		int num_suspended_intf;
		int sample_rate_read_error;

		struct list_head pcm_list; /* list of pcm streams */
		struct list_head ep_list; /* list of audio-related endpoints */

Admin message