[pulseaudio-tickets] [Bug 84878] protocol-native: I get endless underruns when I playback when alsa buffer size is small

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=84878

--- Comment #6 from Alban Browaeys <prahal at yahoo.com> ---
(In reply to Raymond from comment #1)
> seem your sound card support DMA_RESIDUE_GRANULARITY_SEGMENT if the residue
> Residue is updated after each successfully completed segment of the transfer
> 
> as your sound card does not have hardware register to count the number of
> dma transfer
> 
> https://git.kernel.org/cgit/linux/kernel/git/tiwai/sound.git/tree/include/
> linux/dmaengine.h
> 
> 
> @DMA_RESIDUE_GRANULARITY_SEGMENT: Residue is updated after each successfully
>  *  completed segment of the transfer (For cyclic transfers this is after
> each
>  *  period). This is typically implemented by having the hardware generate an
>  *  interrupt after each transferred segment and then the drivers updates the
>  *  outstanding residue by the size of the segment. Another possibility is if
>  *  the hardware supports scatter-gather and the segment descriptor has a
> field
>  *  which gets set after the segment has been completed. The driver then
> counts
>  *  the number of segments without the flag set to compute the residue.
>  * @DMA_RESIDUE_GRANULARITY_BURST: Residue is updated after each transferred
>  *  burst. This is typically only supported if the hardware has a progress
>  *  register of some sort (E.g. a register with the current read/write
> address
>  *  or a register with the amount of bursts/beats/bytes that have been
>  *  transferred or still need to be transferred).

As of now my only clue regarding this is printk output. (In reply to Raymond
from comment #3)
> if your sound card can report DMA_RESIDUE_GRANULARITY_BRUST
> 
> 
> http://mailman.alsa-project.org/pipermail/alsa-devel/2014-September/081501.
> html
> 
> what is the DMA brust size?

I am still looking for this. Sorry for the lag.

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