Tinyalsa: Add support to poll on alsa control
ALSA controls support polling on the kcontrols, this is used in HD-A for
jack notifcation. In tinyalsa we can use this for notfication from sound
card for any events detected by DSP
Upstream:
https://github.com/tinyalsa/tinyalsa/pull/93
https://github.com/tinyalsa/tinyalsa/pull/94
Change-Id: I4193809bfcdb60f4dc11e1c2ad6a07b29cfa80e9
Signed-off-by: Hardik T Shah <hardik.t.shah@intel.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Pankaj Bharadiya <pankaj.laxminarayan.bharadiya@intel.com>
diff --git a/mixer.c b/mixer.c
index 0326c6a..6ea6c0d 100644
--- a/mixer.c
+++ b/mixer.c
@@ -34,6 +34,7 @@
#include <fcntl.h>
#include <errno.h>
#include <ctype.h>
+#include <poll.h>
#include <sys/ioctl.h>
@@ -582,3 +583,46 @@
return -EINVAL;
}
+/** Subscribes for the mixer events.
+ * @param mixer A mixer handle.
+ * @param subscribe value indicating subscribe or unsubscribe for events
+ * @returns On success, zero.
+ * On failure, non-zero.
+ * @ingroup libtinyalsa-mixer
+ */
+int mixer_subscribe_events(struct mixer *mixer, int subscribe)
+{
+ if (ioctl(mixer->fd, SNDRV_CTL_IOCTL_SUBSCRIBE_EVENTS, &subscribe) < 0) {
+ return -1;
+ }
+ return 0;
+}
+
+/** Wait for mixer events.
+ * @param mixer A mixer handle.
+ * @param timeout timout value
+ * @returns On success, 1.
+ * On failure, -errno.
+ * On timeout, 0
+ * @ingroup libtinyalsa-mixer
+ */
+int mixer_wait_event(struct mixer *mixer, int timeout)
+{
+ struct pollfd pfd;
+
+ pfd.fd = mixer->fd;
+ pfd.events = POLLIN | POLLOUT | POLLERR | POLLNVAL;
+
+ for (;;) {
+ int err;
+ err = poll(&pfd, 1, timeout);
+ if (err < 0)
+ return -errno;
+ if (!err)
+ return 0;
+ if (pfd.revents & (POLLERR | POLLNVAL))
+ return -EIO;
+ if (pfd.revents & (POLLIN | POLLOUT))
+ return 1;
+ }
+}