On Thu, Aug 12, 2010 at 06:15:47PM +0800, Randolph Chung wrote: > I have a target that uses iMX27(L) + tlv320aic3x. The kernel tree is > HEAD of linux-arm from about a week ago. > > Simple playback and recording (using aplay and arecord) work fine. > However, I've run into a strange problem when both playback and > capture streams are opened at the same time. > > Consider the attached test program. The capture device is setup with a > period time of 10ms, and the program reads samples in a loop. The > expected result is that I get a sample every 10ms. This works fine if > the playback device is *not* opened (more specifically, if the > hw_params are not set). However if the playback device is opened (#if > 1 code) then I get samples every 20ms, which seems very wrong. > > I have tried using both DMA and FIQ ssi-pcm interfaces and both give > the same strange result. With the FIQ driver, if I instrument the > timer callback, the timer triggers every 10ms but there is only enough > data every 20ms. > > The codec is being driven with a 13MHz MCLK (output from MX27) and the > BCLK and WCLK come from the codec. They seem to have the correct > rates. > > Any ideas? Can anybody else with MX27 hardware verify if my test > program also fails on their target? You should check the return values of the snd_pcm_hw_params_* functions. At least snd_pcm_hw_params_set_channels fails because we currently only support two channels. I'm not sure whether we can support one channel mode without changes to the driver. Sascha -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel