Re: HP PA-RISC harmony driver

[Takashi Iwai <tiwai@suse.de>]

Hi,

At Fri, 6 Dec 2002 20:10:02 +0100,
Laurent Canet wrote:
> 
> Hi,
> 
> I've wrote an ALSA driver for the harmony chipset. This chipset
> is found in some HP PA-RISC workstations. 
> My driver is in very early stage, so I would like your appreciations on
> the code.
 
most of the codes looks fine.

a few points / questions:

- the handling of buffers can be improved.
  so far, it's implemented a bit incorrectly.
  you shouldn't touch runtime->dma_bytes directly.

  if the interrupt period is fixed in HARMONY_BUF_SIZE, the period and
  the buffer size should be restricted via hw constraints:
	- interger-constraint to PERIODS
	- PERIOD_BYTES aligned to HARMONY_BUF_SIZE 

- is mono channel handled correctly?

- a-law and mu-law formats look not implemented.

- disable/enable_interrupts() are necessary in the irq handler?
  also, enable_interrupts() may be called many times.

- it would be safer to have timeouts in some infinite loops...


> The actual state of the driver is 
> -initialisation of the driver works perfectly. 
> -Playback open (with mpg321 -o alsa09) is successful.
> -But after 2-3 interrupts, and the first call to the pointer function, 
> the libao stops the playback (stop trigger) and print an error on stderr 
> (ALSA unknown error 1024). After this, it immediately restart the playback
> 
> Some noise can be heard, but it's sluggish, probably due to printks in the
> interruption routine.
> 
> (Compiling this driver is a little bit hard, since alsa-driver distributions
> don't have any support for the hppa platform. I suggest 'by hand' compiling
> with gcc)
 
it's not too difficult to add the support, copying the parisc comiple
flags from linux kernel, pasting it to the configure script, and
defining CONFIG_* variables, etc.

do you suppose that the driver will be compiled only for PARISC?
then i'll create a directory alsa-driver/parisc and put the stuff
there.


ciao,

Takashi


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