[alsa-devel] fsl_ssi.c: Getting channel slips with fsl_ssi.c in TDM (network) mode.

[Roberto Fichera]

On 10/27/2015 09:11 PM, Nicolin Chen wrote:
> On Tue, Oct 27, 2015 at 08:13:44AM +0100, Markus Pargmann wrote:
>
>>> So, the dma priority doesn't seem to be the issue.  It's now set in
>>> the device tree, and strangely it's set to priority 0 (the highest)
>>> along with the UARTS.  priority 0 is just the highest in the device
>>> tree -- it gets remapped to priority 3 in the sdma driver.  the DT
>>> exposes only 3 levels of DMA priority, low, medium, and high.  I
>>> created a new level that maps to DMA priroity 7 (the highest in the
>>> hardware), but still got the problem.
>>>
>>> So, still something unknown causing dma to miss samples.  must be in
>>> the dma ISR I would assume.  I guess it's time to look into that.
>> Cc Nicolin, Fabio, Shawn
>>
>> Perhaps you have an idea about this?
> Off the top of my head:
>
> 1) Enable TUE0, TUE1, ROE0, ROE1 to see if there is any IRQ trigged.

I'm my case I was never able to see an interrupt triggered when setting both RDMAE and TDMAE
bits in the SIER register.

> 2) Set the watermarks for both TX and RX to 8 while using burst sizes
>    of 6. It'd be nicer to provisionally set these numbers using hard
>    code than your current change depending on fifo_depth as it might
>    be an odd value.
>
> 3) Try to enlarge the ALSA period size in the asound.conf or passing
>    parameters when you do the playback/capture so that the number of
>    interrupts from SDMA may reduce.
>
> You may also see if the reproducibility is somehow reduced or not.
>
> Nicolin
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