On 3/19/07, Takashi Iwai <tiwai@xxxxxxx> wrote: > At Mon, 19 Mar 2007 12:31:16 -0400, > Rich Rattanni wrote: > > > > All: > > > > I have noticed a strange behaviour in the ALSA driver that seems to be > > occur after initiating a power standby and resume. I am working on an > > application that uses FusionSound to playback OGG audio files. When > > the application recognizes it is idle, it tells the OS to enter > > standby mode. Upon resuming from standby, the ALSA API call made by > > fusionsound no longer acts as a blocking read, instead it returns > > immediately. I have confirmed this with Denis Oliver Kropp of the > > DirectFB / FusionSound project. He suggested that the ALSA driver > > should be repaired to prevent this problem from occuring. > > It's not clear what is happening there. > Do you have a small testcase? > > When the suspend/resume happens, the apps is usually requested to call > snd_pcm_resume() and/or snd_pcm_prepare() appropriately to reset the > stream. Otherwise the PCM status is kept as SUSPENDED. > > > Takashi > > > > > The system specifications are... > > Linux - Openembedded distro linux kernel 2.6.20 > > GCC - 4.1.1 > > ALSA - 1.0.13-r1 > > FusionSound - 0.9.26-r0 > > > > I guess I am looking for confirmation of this behavior with ALSA and > > any possible suggestions to patch the driver to operate correctly with > > power management functions under linux. > > > > Thanks in advance, > > Rich > > > > ------------------------------------------------------------------------- > > Take Surveys. Earn Cash. Influence the Future of IT > > Join SourceForge.net's Techsay panel and you'll get the chance to share your > > opinions on IT & business topics through brief surveys-and earn cash > > http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV > > _______________________________________________ > > Alsa-devel mailing list > > Alsa-devel@xxxxxxxxxxxxxxxxxxxxx > > https://lists.sourceforge.net/lists/listinfo/alsa-devel > > > Takashi: I received a reply from Denis Kropp. Here is the source code of FusionSound where the problem occurs. Rich Rattanni schrieb: > I have a post going on the alsa developers mailing list addressing > this issue, they are asking for the specific source code of the > problem. Could you tell me where in the code to look for that loop > that reads the sound device? It starts in src/core/core_sound.c at line 459: static void * sound_thread( DirectThread *thread, void *arg ) The (most likely) non-blocking write is done at line 654: fs_device_write( core->device, output, mixed >> 1 ); Which is ending up in drivers/alsa.c at line 255: static void device_write( void *device_data, void *samples, unsigned int size ) { AlsaDeviceData *data = device_data; snd_pcm_uframes_t frames = size; snd_pcm_sframes_t r; u8 *src; src = samples; while (frames) { r = snd_pcm_writei( data->handle, src, frames ); if (r < 0) { r = snd_pcm_prepare( data->handle ); if (r < 0) { D_WARN( "FusionSound/Device/ALSA: snd_pcm_writei() failed: %s\n", snd_strerror( r ) ); break; } continue; } frames -= r; src += snd_pcm_frames_to_bytes( data->handle, r ); } } I don't know about these APIs, but at least one of snd_pcm_writei() and snd_pcm_prepare() should block, otherwise the mixer loop has no sleep... ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys-and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.sourceforge.net/lists/listinfo/alsa-devel
