Re: Fwd: [usb-midi-fw-devel] proposal concerning cooperation of snd-usb-usx2x.o and rbtload

[Takashi Iwai <tiwai@suse.de>]

Hi Karsten,

At Fri, 29 Aug 2003 13:29:17 +0200,
Karsten Wiese wrote:
> 
> [1  <text/plain; us-ascii (7bit)>]
> hi,
> please check the hotplug strategy outlined in the forward.
> If it's ok, i'll prepare a next patch based on what is in the forward.
(snip)
> hi colegas,
> 
> have been trying the 0.1 and yes, the fpga code does it also for us428 !
> concerning cooperation of snd-usb-us428.o and rbtload i've implemented a  
> hack:
> when a hotplug occurs (EZUSB Firmware not being looked at here, works as 
> before), the kernel 
> 1.) asks snd-usb-us428.o, if it wants to have the device. snd-usb-us428.o says 
> 'yes!'. this latest snd-usb-us428.o will not start any ALSA-Activity in this 
> stage. It just owns the interface to the us428 (and implements 2 new 
> ioctl-able entriepoints).

hmm, what would be a gain by using ioctl?


> 2.) starts rbtload (by means of the hotplug-scripts) to download the fpga 
> code. this hacked rbtload does the download by means of standard ioctl() - 
> calls to snd-usb-us428.o. Thus we don't need libusb here anymore. (libusb is 
> still used here for minimizing changing efforts.) if download is finished, 
> snd-usb-us428.o ALSA-Activities are started by another ioctl to 
> snd-usb-us428.o.

you can create a hwdep device in the probe callback of snd-usb-us428,
and later create pcm and mixer devices dynamically after the firmware
is loaded.
this method is used in some other drivers like vx drivers.
you can use own mmap and ioctl for this device, too, if you want.

> 
> Result: us428 works as before.
> 
> What do you think about setting up a 0.2 this way? 
> 
> If you might wonder why snd-usb-us428 is still seperate from snd-usb-audio:
> - us428 (and possibly usx2x) use a non standard way of synching audio in & 
> out.

this is ok, we can merge later.

> - us428 and us224 (don't know about us122) have those knobs & sliders. they 
> are also special.

can't you implement these as standard mixer elements?
then all mixer programs can access them.


thanks,

Takashi


-------------------------------------------------------
This sf.net email is sponsored by:ThinkGeek
Welcome to geek heaven.
http://thinkgeek.com/sf