Commit 06ffc1eb authored by Eldad Zack's avatar Eldad Zack Committed by Takashi Iwai

ALSA: usb-audio: UAC2: do clock validity check earlier

Move the check that parse_audio_format_rates_v2() do after
receiving the clock source entity ID directly into the find
function and add a validation flag to the function.

This patch does not introduce any logic flow change.

It is provided to allow introducing automatic clock switching
easier later. By moving this uac_clock_source_is_valid callsite,
2 additional callsites can be avoided.
Signed-off-by: default avatarEldad Zack <>
Signed-off-by: default avatarTakashi Iwai <>
parent f6a8bc70
......@@ -131,7 +131,8 @@ static bool uac_clock_source_is_valid(struct snd_usb_audio *chip, int source_id)
static int __uac_clock_find_source(struct snd_usb_audio *chip,
int entity_id, unsigned long *visited)
int entity_id, unsigned long *visited,
bool validate)
struct uac_clock_source_descriptor *source;
struct uac_clock_selector_descriptor *selector;
......@@ -148,8 +149,15 @@ static int __uac_clock_find_source(struct snd_usb_audio *chip,
/* first, see if the ID we're looking for is a clock source already */
source = snd_usb_find_clock_source(chip->ctrl_intf, entity_id);
if (source)
return source->bClockID;
if (source) {
entity_id = source->bClockID;
if (validate && !uac_clock_source_is_valid(chip, entity_id)) {
snd_printk(KERN_ERR "usb-audio:%d: clock source %d is not valid, cannot use\n",
chip->dev->devnum, entity_id);
return -ENXIO;
return entity_id;
selector = snd_usb_find_clock_selector(chip->ctrl_intf, entity_id);
if (selector) {
......@@ -164,7 +172,7 @@ static int __uac_clock_find_source(struct snd_usb_audio *chip,
/* Selector values are one-based */
if (ret > selector->bNrInPins || ret < 1) {
"%s(): selector reported illegal value, id %d, ret %d\n",
__func__, selector->bClockID, ret);
......@@ -172,14 +180,14 @@ static int __uac_clock_find_source(struct snd_usb_audio *chip,
return __uac_clock_find_source(chip, selector->baCSourceID[ret-1],
visited, validate);
/* FIXME: multipliers only act as pass-thru element for now */
multiplier = snd_usb_find_clock_multiplier(chip->ctrl_intf, entity_id);
if (multiplier)
return __uac_clock_find_source(chip, multiplier->bCSourceID,
visited, validate);
return -EINVAL;
......@@ -195,11 +203,12 @@ static int __uac_clock_find_source(struct snd_usb_audio *chip,
* Returns the clock source UnitID (>=0) on success, or an error.
int snd_usb_clock_find_source(struct snd_usb_audio *chip, int entity_id)
int snd_usb_clock_find_source(struct snd_usb_audio *chip, int entity_id,
bool validate)
DECLARE_BITMAP(visited, 256);
memset(visited, 0, sizeof(visited));
return __uac_clock_find_source(chip, entity_id, visited);
return __uac_clock_find_source(chip, entity_id, visited, validate);
static int set_sample_rate_v1(struct snd_usb_audio *chip, int iface,
......@@ -275,18 +284,11 @@ static int set_sample_rate_v2(struct snd_usb_audio *chip, int iface,
struct usb_device *dev = chip->dev;
__le32 data;
int err, cur_rate, prev_rate;
int clock = snd_usb_clock_find_source(chip, fmt->clock);
int clock = snd_usb_clock_find_source(chip, fmt->clock, true);
if (clock < 0)
return clock;
if (!uac_clock_source_is_valid(chip, clock)) {
/* TODO: should we try to find valid clock setups by ourself? */
snd_printk(KERN_ERR "%d:%d:%d: clock source %d is not valid, cannot use\n",
dev->devnum, iface, fmt->altsetting, clock);
return -ENXIO;
prev_rate = get_sample_rate_v2(chip, iface, fmt->altsetting, clock);
data = cpu_to_le32(rate);
......@@ -5,6 +5,7 @@ int snd_usb_init_sample_rate(struct snd_usb_audio *chip, int iface,
struct usb_host_interface *alts,
struct audioformat *fmt, int rate);
int snd_usb_clock_find_source(struct snd_usb_audio *chip, int entity_id);
int snd_usb_clock_find_source(struct snd_usb_audio *chip, int entity_id,
bool validate);
#endif /* __USBAUDIO_CLOCK_H */
......@@ -280,7 +280,7 @@ static int parse_audio_format_rates_v2(struct snd_usb_audio *chip,
struct usb_device *dev = chip->dev;
unsigned char tmp[2], *data;
int nr_triplets, data_size, ret = 0;
int clock = snd_usb_clock_find_source(chip, fp->clock);
int clock = snd_usb_clock_find_source(chip, fp->clock, false);
if (clock < 0) {
snd_printk(KERN_ERR "%s(): unable to find clock source (clock %d)\n",
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