* Audio and mpc5200 bestcomm tasks
@ 2009-05-21 18:52 Jon Smirl
2009-05-22 4:33 ` Grant Likely
0 siblings, 1 reply; 2+ messages in thread
From: Jon Smirl @ 2009-05-21 18:52 UTC (permalink / raw)
To: Grant Likely, linuxppc-dev
ALSA really wants to dynamically know the address of the current DMA
location while transfers are active. This is an important piece of
implementing pause/resume. Pause doesn't work too well if there is 2s
of music already queued. The work around is to know the sample rate
and use the jiffy count to estimate how far into the buffer DMA has
progressed. But that's not as accurate as just asking the DMA
hardware.
I poked around in the SRAM data and couldn't find the address. Is it
there or can the Bestcomm tasks be modified to leave it somewhere
visible?
--
Jon Smirl
jonsmirl@gmail.com
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: Audio and mpc5200 bestcomm tasks
2009-05-21 18:52 Audio and mpc5200 bestcomm tasks Jon Smirl
@ 2009-05-22 4:33 ` Grant Likely
0 siblings, 0 replies; 2+ messages in thread
From: Grant Likely @ 2009-05-22 4:33 UTC (permalink / raw)
To: Jon Smirl; +Cc: linuxppc-dev
On Thu, May 21, 2009 at 12:52 PM, Jon Smirl <jonsmirl@gmail.com> wrote:
> ALSA really wants to dynamically know the address of the current DMA
> location while transfers are active. This is an important piece of
> implementing pause/resume. Pause doesn't work too well if there is 2s
> of music already queued. The work around is to know the sample rate
> and use the jiffy count to estimate how far into the buffer DMA has
> progressed. But that's not as accurate as just asking the DMA
> hardware.
>
> I poked around in the SRAM data and couldn't find the address. Is it
> there or can the Bestcomm tasks be modified to leave it somewhere
> visible?
It may be possible, but I haven't made any attempts at writing
bestcomm task code. I've got no idea how difficult it would be.
g.
--
Grant Likely, B.Sc., P.Eng.
Secret Lab Technologies Ltd.
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