ALSA: usb-audio: assume valid clock

If the interface can't report a clock's validity, assume that it's
valid.
Signed-off-by: Daniel Mack <zonque@gmail.com>
Reported-by: Vicente Joel <vicentejoel@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/usb/clock.c

@@ -104,6 +104,15 @@ static bool uac_clock_source_is_valid(struct snd_usb_audio *chip, int source_id)
 	int err;
 	unsigned char data;
 	struct usb_device *dev = chip->dev;
+	struct uac_clock_source_descriptor *cs_desc =
+		snd_usb_find_clock_source(chip->ctrl_intf, source_id);
+
+	if (!cs_desc)
+		return 0;
+
+	/* If a clock source can't tell us whether it's valid, we assume it is */
+	if (!uac2_control_is_readable(cs_desc->bmControls, UAC2_CS_CONTROL_CLOCK_VALID))
+		return 1;
 
 	err = snd_usb_ctl_msg(dev, usb_rcvctrlpipe(dev, 0), UAC2_CS_CUR,
 			      USB_TYPE_CLASS | USB_RECIP_INTERFACE | USB_DIR_IN,
@@ -114,7 +123,7 @@ static bool uac_clock_source_is_valid(struct snd_usb_audio *chip, int source_id)
 	if (err < 0) {
 		snd_printk(KERN_WARNING "%s(): cannot get clock validity for id %d\n",
 			   __func__, source_id);
-		return err;
+		return 0;
 	}
 
 	return !!data;