Hello All, I am desiging a TI sound card driver on my ARM board using Linux 2.6.18. The ARM SOC uses IIS and IIC to control this soud codec chip. I found a stranger problem reltaed to the sound PCM data: The data transfered by DMA is different from the data I write to the sound device! If I perform this command: cat test.txt > /dev/dsp using the printk to trace the data flow, I found the snd_pcm_oss_write function write all the data in test.txt to substream->runtime->oss.buffer. However, In the snd_pcm_plug_write_transfer function, the channel changes and the data is different: original data(text.txt): [00]=30 [01]=31 [02]=32 [03]=33 [04]=34 [05]=35 [06]=36 [07]=37 [08]=38 [09]=39 [10]=0a The modified data: [00]=00 [01]=b0 [02]=00 [03]=b0 [04]=00 [05]=b1 [06]=00 [07]=b1 [08]=00 [09]=b2 [10]=00 [11]=b2 [12]=00 [13]=b3 [14]=00 [15]=b3 It seems that all the 8th bit are changed to 1. I am not sure if it is correct. Thank you! Tyler Li ------------------------------------------------------------------------- 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
