Re: period crossing page boundary

[Giuliano Pochini <pochini@shiny.it>]

> > I'm facing another *£%@ problem. When period size is a multiple or
> > submultiple of PAGE_SIZE, it works fine, but when it isn't, sound
> > clicks, pops, repeapeapeats, skps :(( And since the period never crosses
> > physically the page boundary because I split it when it happens, I can't
> > imagine what's wrong. Perhaps some of you had the same problem.
> > 
> > .period callback does this:
> 
> do you mean pointer callback?

Yes, sorry. 

> > bufsize=substream->runtime->periods*substream->runtime->period_size;
>
> you already have substream->runtime->buffer_size for this.
They are different:

[aplay <no options> track.wav]
Mar 19 19:21:23 localhost kernel: pcm_hw_params (bufsize=88200 periods=3
persize=22052) 

bufsize==88200 != 3*22052 == 66156 

> > //addr==number of bytes transferred.
> > pos=bytes_to_frames(substream->runtime, addr);
> > return(pos%bufsize);
>
> i suppose addr is updated in the interrupt handler, right?

No, I read it from the hardware every time. I tried to store the value
in the irq handler and it's the same.

>
> > Here is a log of sg list construction:
> > [...]
>
> the logs seem fine.
>
> did you set up page callback, too?

Yes I did.

> were the irqs issued correctly with the 1.5 page periods?
> i mean, at the proper timing?

Yes, I believe. When period size is 2048 or 1024 it works fine. I put a
printk in the pointer callback to monitor the frame position and it always
seems correct despite the bad output. "irq" is a command I insert in the
sg list, because the hw don't generate it automatically at the and of each
block. IMO the bug is around the .pointer callback function.

> maybe it would be easier to debug if you show the actual code and the
> hardware spec...

I'm writing my driver around the open source generic driver released by
the manufacturer (in C++ argh!). I'm trying to keep the generic code
as-is to make upgrades to future releases easier. I don't have hw specs
but the sources are full of comments. As far as I can see there are no
hw limits about the size of the sg list and its entries.

You can get my (very-ugly-pre-alpha) sources here:
http://space.virgilio.it/g_pochini@virgilio.it/ea.tgz
and the generic driver here:
http://www.echoaudio.com/Downloads/Developer/EchoGenericDriverA0.zip


Bye.




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