fsoaudiod: alsaloop gsmvoice_alsa_forwarder plugin: fix high CPU usage before call.

Thanks a lot DocScrutinizer05 on #openmoko-cdevel FreeNode IRC Channel:
  Jun 04 23:26:42 <gnutoo>        there is a call incomming or outgoing
  Jun 04 23:26:48 <gnutoo>        fsogsmd knows it
  Jun 04 23:26:57 <gnutoo>        so it tells it on dbus
  Jun 04 23:27:06 <gnutoo>        fsoaudiod which is listenning on dbug get that message
  Jun 04 23:27:15 <gnutoo>        and activate the alsaloop based plugin
  Jun 04 23:27:17 <gnutoo>        however....
  [...]
  #Jun 04 23:27:17 *       backb0ne__ (~backb0ne@27.Red-88-26-71.staticIP.rima-tde.net) has joined #openmoko-cdevel
  Jun 04 23:27:28 <gnutoo>        there is a time between that activation and when the modem is ready
  Jun 04 23:27:39 <gnutoo>        because the modem is the one who is clock master
  Jun 04 23:27:53 <DocScrutinizer05>      ouch
  Jun 04 23:27:57 <gnutoo>        so then what happens in alsaloop is that poll() returns too fast
  Jun 04 23:28:18 <DocScrutinizer05>      instantly with -EAGAIN I guess
  Jun 04 23:28:48 <gnutoo>        like the asoc poll() is broken for our case where the clocks master are from the modem
  Jun 04 23:29:05 <DocScrutinizer05>      in which case alsaloop SHOULD call a usleep(1000)
  Jun 04 23:29:35 <gnutoo>        that poll() returning too fast (30us) instead of 30000000us or something big like that causes the 100% CPU usage
  Jun 04 23:29:51 <gnutoo>        and then the 100% CPU usage causes other problem once the modem is started
  Jun 04 23:29:55 <gnutoo>        because it doesn't sotp
  Jun 04 23:29:57 <gnutoo>        *stop
  [...]
  Jun 04 23:30:00 <DocScrutinizer05>      yep, that's why alsaloop needs a usleep()
  [...]
  Jun 04 23:33:21 <DocScrutinizer05>      not if you put it at the right location
  Jun 04 23:33:31 <DocScrutinizer05>      immediately *before* the poll()

Signed-off-by: Denis 'GNUtoo' Carikli <GNUtoo@no-log.org>

1 files changed, 1 insertions, 0 deletions

diff --git a/fsoaudiod/src/plugins/gsmvoice_alsa_forwarder/alsaloop.c b/fsoaudiod/src/plugins/gsmvoice_alsa_forwarder/alsaloop.c
index 2b4c9e7b..3d4068be 100644
--- a/fsoaudiod/src/plugins/gsmvoice_alsa_forwarder/alsaloop.c
+++ b/fsoaudiod/src/plugins/gsmvoice_alsa_forwarder/alsaloop.c
@@ -741,6 +741,7 @@ static void thread_job1(void *_data)
 		}
 		if (verbose > 10)
 			gettimeofday(&tv1, NULL);
+		usleep(1000);
 		err = poll(pfds, j, wake);
 		if (err < 0)
 			err = -errno;