Dear Alsa developers, I would like to take the opportunity and ask you for your best practice and experience. I have an AC'97 codec connected via a TDM bus to my CPU. Talking with the codec is working already, so the control (mixer) interface is working. For transferring data between TDM bus and CPU I use DMA of course. The layout of the buffers is organised in a way, where every AC97 slot has multiple fragments of continuous memory (up to 2048 bytes per fragment). For example, I could have 32 pieces of 1024 bytes of memory for left channel. This would be the same for every channel (16 channels). So the buffer layout is static once created and the DMA is running all the time in order to send or receive AC97 commands. My current way is, to implement the copy and silence callbacks. In copy I would then copy the data to the "next" fragment. With this solution I can not support mmap. Also I'm a little bit unsure of the pointer callback here. Should I implement it? What is it suppose to return? But the biggest problem here is to synchronise the DMA and the copy callback somehow. Or do you think it is ok to just write to the next fragment and let the DMA run freely? Another way I can imagine is, to have a memory area holding the PCM data and then copy the data in my interrupt to the next fragment. Synchronising with DMA would be no problem here and mmap would also be supported. But to copy data in an interrupt is somehow.. not-DMA-like. So I don't like that solution so much. I'm looking forward to learning from your experience. Maybe you have some hints or an Alsa driver in mind which faced the same problems? Thanks in advance, Henry ------------------------------------------------------------------------- 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
