ALSA: usb-audio: UAC2: try to find and switch to valid clock

If a selector is available on a device, it may be pointing to a
clock source which is currently invalid.
If there is a valid clock source which can be selected, switch
to it.

Signed-off-by: Eldad Zack <eldad@fogrefinery.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 66 insertions, 3 deletions

diff --git a/sound/usb/clock.c b/sound/usb/clock.c
index 0c98f52a1c9c..d7ab2d75aefd 100644
--- a/sound/usb/clock.c
+++ b/sound/usb/clock.c
@@ -99,6 +99,41 @@ static int uac_clock_selector_get_val(struct snd_usb_audio *chip, int selector_i
         return buf;
 }
 
+static int uac_clock_selector_set_val(struct snd_usb_audio *chip, int selector_id,
+                                        unsigned char pin)
+{
+        int ret;
+
+        ret = snd_usb_ctl_msg(chip->dev, usb_sndctrlpipe(chip->dev, 0),
+                              UAC2_CS_CUR,
+                              USB_RECIP_INTERFACE | USB_TYPE_CLASS | USB_DIR_OUT,
+                              UAC2_CX_CLOCK_SELECTOR << 8,
+                              snd_usb_ctrl_intf(chip) | (selector_id << 8),
+                              &pin, sizeof(pin));
+        if (ret < 0)
+                return ret;
+
+        if (ret != sizeof(pin)) {
+                snd_printk(KERN_ERR
+                        "usb-audio:%d: setting selector (id %d) unexpected length %d\n",
+                        chip->dev->devnum, selector_id, ret);
+                return -EINVAL;
+        }
+
+        ret = uac_clock_selector_get_val(chip, selector_id);
+        if (ret < 0)
+                return ret;
+
+        if (ret != pin) {
+                snd_printk(KERN_ERR
+                        "usb-audio:%d: setting selector (id %d) to %x failed (current: %d)\n",
+                        chip->dev->devnum, selector_id, pin, ret);
+                return -EINVAL;
+        }
+
+        return ret;
+}
+
 static bool uac_clock_source_is_valid(struct snd_usb_audio *chip, int source_id)
 {
         int err;
@@ -161,7 +196,7 @@ static int __uac_clock_find_source(struct snd_usb_audio *chip,
 
         selector = snd_usb_find_clock_selector(chip->ctrl_intf, entity_id);
         if (selector) {
-                int ret;
+                int ret, i, cur;
 
                 /* the entity ID we are looking for is a selector.
                  * find out what it currently selects */
@@ -179,8 +214,35 @@ static int __uac_clock_find_source(struct snd_usb_audio *chip,
                         return -EINVAL;
                 }
 
-                return __uac_clock_find_source(chip, selector->baCSourceID[ret-1],
+                cur = ret;
+                ret = __uac_clock_find_source(chip, selector->baCSourceID[ret - 1],
                                                visited, validate);
+                if (!validate || ret > 0)
+                        return ret;
+
+                /* The current clock source is invalid, try others. */
+                for (i = 1; i <= selector->bNrInPins; i++) {
+                        int err;
+
+                        if (i == cur)
+                                continue;
+
+                        ret = __uac_clock_find_source(chip, selector->baCSourceID[i - 1],
+                                visited, true);
+                        if (ret < 0)
+                                continue;
+
+                        err = uac_clock_selector_set_val(chip, entity_id, i);
+                        if (err < 0)
+                                continue;
+
+                        snd_printk(KERN_INFO
+                                "usb-audio:%d: found and selected valid clock source %d\n",
+                                chip->dev->devnum, ret);
+                        return ret;
+                }
+
+                return -ENXIO;
         }
 
         /* FIXME: multipliers only act as pass-thru element for now */
@@ -284,8 +346,9 @@ 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, true);
+        int clock;
 
+        clock = snd_usb_clock_find_source(chip, fmt->clock, true);
         if (clock < 0)
                 return clock;