ALSA: usb-audio: Support read-only clock selector control

Clock selector control might be read-only. Add corresponding checks
to prevent sending control requests that would fail.

Signed-off-by: Alexander Tsoy <alexander@tsoy.me>
Link: https://lore.kernel.org/r/20240125205457.28258-1-alexander@tsoy.me
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/sound/usb/clock.c b/sound/usb/clock.c
index 94e4aaeafe588464496dbfcecf761033b21a0990..7b259641adb5158c448d28fa2c4c816a1abdd800 100644 (file)
--- a/sound/usb/clock.c
+++ b/sound/usb/clock.c
@@ -261,6 +261,8 @@ static int __uac_clock_find_source(struct snd_usb_audio *chip,
        int ret, i, cur, err, pins, clock_id;
        const u8 *sources;
        int proto = fmt->protocol;
+       bool readable, writeable;
+       u32 bmControls;
 
        entity_id &= 0xff;
 
@@ -292,11 +294,27 @@ static int __uac_clock_find_source(struct snd_usb_audio *chip,
                sources = GET_VAL(selector, proto, baCSourceID);
                cur = 0;
 
+               if (proto == UAC_VERSION_3)
+                       bmControls = le32_to_cpu(*(__le32 *)(&selector->v3.baCSourceID[0] + pins));
+               else
+                       bmControls = *(__u8 *)(&selector->v2.baCSourceID[0] + pins);
+
+               readable = uac_v2v3_control_is_readable(bmControls,
+                                                       UAC2_CX_CLOCK_SELECTOR);
+               writeable = uac_v2v3_control_is_writeable(bmControls,
+                                                         UAC2_CX_CLOCK_SELECTOR);
+
                if (pins == 1) {
                        ret = 1;
                        goto find_source;
                }
 
+               /* for now just warn about buggy device */
+               if (!readable)
+                       usb_audio_warn(chip,
+                               "%s(): clock selector control is not readable, id %d\n",
+                               __func__, clock_id);
+
                /* the entity ID we are looking at is a selector.
                 * find out what it currently selects */
                ret = uac_clock_selector_get_val(chip, clock_id);
@@ -326,7 +344,7 @@ static int __uac_clock_find_source(struct snd_usb_audio *chip,
                if (ret > 0) {
                        /* Skip setting clock selector again for some devices */
                        if (chip->quirk_flags & QUIRK_FLAG_SKIP_CLOCK_SELECTOR ||
-                           pins == 1)
+                           pins == 1 || !writeable)
                                return ret;
                        err = uac_clock_selector_set_val(chip, entity_id, cur);
                        if (err < 0)
@@ -337,6 +355,9 @@ static int __uac_clock_find_source(struct snd_usb_audio *chip,
                        return ret;
 
        find_others:
+               if (!writeable)
+                       return -ENXIO;
+
                /* The current clock source is invalid, try others. */
                for (i = 1; i <= pins; i++) {
                        if (i == cur)