Hi, I have a 16 bit alsa driver that allocates kernel memory, uses SNDRV_DMA_TYPE_CONTINUOUS, snd_dma_continuous_data(GFP_KERNEL), and specifies MMAP | MMAP_VALID et.al. The idea is that user space writes into this mmapped memory, and from the kernel I send the data to the sound device. For testing, I've modified this driver to check the values in the buffer to be increasing 1, 2, 3, etc.. and written a test program that opens alsa and writes these values in a buffer using snd_pcm_writei. I observe that some samples are from the previous iteration in the buffer, but the surrounding samples are ok. For example with 2000 frames buffer size, period size 500, then in the third iteration I read 2000, 4001, 4002, ... instead of 4000, 4001, 4002, ... Memory test ran ok, so that's not the problem, and also linux is running stable. The rate is 8 khz, and I'm not getting alsa underruns. Has anyone seen this behaviour before, and how to fix it ? Or, any hints how to reproduce the alsa mmap behaviour in a smaller software stack ? Thanks in advance, Micha ------------------------------------------------------------------------- Using Tomcat but need to do more? Need to support web services, security? Get stuff done quickly with pre-integrated technology to make your job easier. Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642 _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.sourceforge.net/lists/listinfo/alsa-devel
