On Wed, Oct 21, 2015 at 12:32 AM, arnaud.mouiche@xxxxxxxxxxx <arnaud.mouiche@xxxxxxxxxxx> wrote: > > > Le 20/10/2015 19:43, Caleb Crome a écrit : >> Hi Arnaud, >> My root filesystem already had that firmware in it (the kernel >> didn't have the kernel patch, but when I applied that patch, the >> generated sdma script was identical. >> >> So, unfortunately, that's not the problem with the channel slipping. >> Any other thoughts on why the channel would slip? Or pointers on how >> to diagnose? I have an oscilloscope & know how to use it :-) Also, I >> can flip a GPIO to watch for timing of interrupts, etc (although I >> haven't done that yet). >> >> >> Thanks, >> -Caleb > > > Hello Caleb, > > In your situation, I would: > - check if TUE0/1 flag never rise (Transmitter Underrun) by activating the > TUE0/1IE bit to generate related interrupts. It looks like already enabled > in 4.0 by collecting statistics with fsl_ssi_dbg_isr(). Despite there is no > printk message on underrun, stats can be read from > /sys/kernel/debug/xxxx.ssi/stats. Heh, I checked that and I couldn't get the fsl_ssi_dbg_isr to trigger ever, for any reason. Somehow interrupts seem to be disabled in the SSI driver, and I can't figure out how to enable them. It appears that the only interrupt required is the DMA interrupt, and SSI interrupts are not checked. The /sys/kernel/debug/xxxx.ssi/stats file reads all zeros no matter what, even during playing, and even after the user space detects underruns. > > - I suspect the dma is not fast enough to fill the FIFO. may be you should > dig to check how SDMA priority are configured amongs the differents DMA > channels. > Not something I already look at before. A quick look suggest that > DMA_PRIO_HIGH is _NOT_ configured by the fsl_ssi.c driver (wheras the > imx-ssi.c did) Ah ha! Perhaps that's it. I will check into that. Maybe that's the root cause. Thanks so much. -Caleb > > Regards, > Arnaud > > _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
