At Thu, 08 Feb 2007 14:12:37 +0100, Johannes Berg wrote: > > From: Paul Mackerras <paulus@xxxxxxxxx> > > This fixes the problem of getting extra bytes inserted at the > beginning of a recording when using the Apple i2s interface and DBDMA > controller. It turns out that we can't just abort the DMA; we have to > let it stop at the end of a command, and then wait for the S7 bit to > be set before turning off the DBDMA controller. Doing that for > playback doesn't seem to be necessary, but doesn't hurt either. > > We use the technique used by the Darwin driver: make each transfer > command branch to a stop command if the S0 status bit is set. Thus we > can ask the DMA controller to stop at the end of the current command > by setting S0. > > The interrupt routine now looks at and clears the status word of the > DBDMA command ring. This is necessary so it can know when the DBDMA > controller has seen that S0 is set, and so when it should look for the > DBDMA controller being stopped and S7 being set. This also ended up > simplifying the calculation in i2sbus_pcm_pointer. > > Tested on a 15 inch albook. > > Signed-off-by: Paul Mackerras <paulus@xxxxxxxxx> > > I modified this patch and added the suspend/resume bits to it to get my > powermac into a decent state when playing sound across suspend to disk > that has a different bitrate from what the firmware programs the > hardware to. > > I also added the SNDRV_PCM_INFO_JOINT_DUPLEX flag because it seemed the > right thing to do and I was looking at the info stuff. > > Signed-off-by: Johannes Berg <johannes@xxxxxxxxxxxxxxxx> Thanks, applied to ALSA tree now. Should be merged to 2.6.21. Takashi ------------------------------------------------------------------------- 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
