Re: [PATCH 3/3] echoaudio: Address bugs in the interrupt handling

[Giuliano Pochini <pochini@shiny.it>]

On Wed, 17 Jun 2020 12:14:42 +0100 (BST)
Mark Hills <mark@xwax.org> wrote:

> On Wed, 17 Jun 2020, Giuliano Pochini wrote:
> [...]
> > -	pipe->position += step;  /* bytes */
> > -
> > -	buffer_bytes = frames_to_bytes(runtime, runtime->buffer_size);
> > -
> > -	while (pipe->position >= buffer_bytes)
> > -		pipe->position -= buffer_bytes;
> > -
> >  	return 1;
> 
> I think this risks returning to a case where it concludes nothing
> advances if the counter advances by a whole buffer?

Yes, it can, but you can detect that case checking for step >= period_bytes.


> You might be able to do the comparison before wrapping pipe_position, but 
> hopefully you'll consider my patch in reply to Takashi has more clarity.

Your patch is very interesting. I didn't take into account the idea of
advancing the position by full periods only. If the PCM subsystem hasn't
changed much since I last checked (I wrote the driver many years ago), it
should work fine (and I'm sure you tested it). But I don't know if
something else requires better resolution.


-- 
Giuliano.