help needed on how to autoload snd-usb-midi

help needed on how to autoload snd-usb-midi

[karsten wiese]

Hi,

I am in the process of updating the tascam us-428
patch for alsa-current and need some hints:
formerly the snd-usb-us428 issued 
"request_module( "snd-usb-midi");"
to load that module. this doesn't work with
alsa-current anymore as the snd-usb-audio
initialisation, which is triggered, conflicts with the
initialisation of snd-usb-us428.
thus I deleted that "request_module( "snd-usb-midi");"
from snd_usb_us428.
I remember from some Mail on this list, that
snd-usb-midi  would be autoloaded if a users process
accesses a mididevice, which has been created by 
"snd_seq_device_new( ...SNDRV_SEQ_DEV_ID_USBMIDI)".
this does not happen here now.
what do I miss?
for the tests I use the bristolsynth with
"./startBristol -alsa -audiodev hw:1 -mididev hw:1"
having issued "modprobe snd-usb-midi" before,
everythingg works as expected. otherwise 
"Could not open the MIDI interface.
Error opening midi device hw:1, exiting midi thread"

TIA, Karsten

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Re: help needed on how to autoload snd-usb-midi

[Clemens Ladisch]

karsten wiese wrote:
> I am in the process of updating the tascam us-428
> patch for alsa-current and need some hints:
> formerly the snd-usb-us428 issued
> "request_module( "snd-usb-midi");"
> to load that module. this doesn't work with
> alsa-current anymore as the snd-usb-audio
> initialisation, which is triggered, conflicts with the
> initialisation of snd-usb-us428.
> thus I deleted that "request_module( "snd-usb-midi");"
> from snd_usb_us428.

snd-usb-midi isn't anymore an independent driver, it has been integrated
into snd-usb-audio (as you've seen), although it's still a separate
module. In theory, it may be possible to do the same stuff as
snd_usb_create_midi_interface() to make it load correctly.

IMHO the "best" solution would be to add a quirk to usbaudio.c, instead of
writing an entirely separate driver with most of the code duplicated. I
didn't look at your patch in full length, but it seems to me that the
changes needed would be firmware loading (best done in a separate driver
or a userspace program) and adding some information about supported audio
formats/bitrates. (I'm sure I've missed something. :)

> I remember from some Mail on this list, that
> snd-usb-midi  would be autoloaded if a users process
> accesses a mididevice, which has been created by
> "snd_seq_device_new( ...SNDRV_SEQ_DEV_ID_USBMIDI)".
> this does not happen here now.

Autoloading happens if there is an alias for snd-card-x (x derived from
the client number) in modules.conf, and if the card driver calls
snd_seq_device_new() for the sequencer driver. (BTW: there was a bug with
autoloading sequencer drivers which has been fixed yesterday)


HTH Clemens



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Re: help needed on how to autoload snd-usb-midi

[karsten wiese]

Clemens Ladisch schrieb: 
> karsten wiese wrote:
> > I am in the process of updating the tascam us-428
> > patch for alsa-current and need some hints:
> > formerly the snd-usb-us428 issued
> > "request_module( "snd-usb-midi");"
> > to load that module. this doesn't work with
> > alsa-current anymore as the snd-usb-audio
> > initialisation, which is triggered, conflicts with
> the
> > initialisation of snd-usb-us428.
> > thus I deleted that "request_module(
> "snd-usb-midi");"
> > from snd_usb_us428.
> 
> snd-usb-midi isn't anymore an independent driver, it
> has been integrated
> into snd-usb-audio (as you've seen), although it's
> still a separate
> module. In theory, it may be possible to do the same
> stuff as
> snd_usb_create_midi_interface() to make it load
> correctly.
here is the routine that is used in snd-usb-us428:
static int snd_us428_create_usbmidi( snd_card_t* card
)
{
#if defined(CONFIG_SND_SEQUENCER) ||
defined(CONFIG_SND_SEQUENCER_MODULE)
	static snd_usb_audio_quirk_t quirk = {
		.vendor_name =	"TASCAM",
		.product_name =	"US-428",
		.ifnum = 	0,
		.type = QUIRK_MIDI_FIXED_ENDPOINT,
		.data = & (const snd_usb_midi_endpoint_info_t) {
			.epnum =	6,
			.out_cables =	3,
			.in_cables =	3
			}
	};
	snd_seq_device_t *seq_device;
	snd_usb_midi_t *umidi;
	int err;

	err = snd_seq_device_new( card, us428(
card)->chip.next_seq_device,
				 SNDRV_SEQ_DEV_ID_USBMIDI,
				 sizeof(snd_usb_midi_t), &seq_device);
	if (err < 0)
		return err;
	us428( card)->chip.next_seq_device++;
	strcpy(seq_device->name, card->shortname);
	umidi = (snd_usb_midi_t
*)SNDRV_SEQ_DEVICE_ARGPTR(seq_device);
	umidi->chip = &us428( card)->chip;
	umidi->ifnum = 0;
	umidi->quirk = &quirk;
	umidi->seq_client = -1;
#endif
	return 0;
}
its a copy-change of usb-audio. something wrong here ?
cannot be completely wrong: if snd-usb-midi is loaded
manually,
everything works ok.

> 
> IMHO the "best" solution would be to add a quirk to
> usbaudio.c, instead of
> writing an entirely separate driver with most of the
> code duplicated. I
> didn't look at your patch in full length, but it
> seems to me that the
> changes needed would be firmware loading (best done
> in a separate driver
> or a userspace program) and adding some information
> about supported audio
> formats/bitrates. (I'm sure I've missed something.
> :)
the us-428 audio is very nonstandard:
it is necessary to know how many frames are just
recorded to be able to playback without unwanted
crackles. I found no other way to determine the exact
samplerate. furthermore there are the hardware knobs,
sliders and lights, the digital in switch....

> 
> > I remember from some Mail on this list, that
> > snd-usb-midi  would be autoloaded if a users
> process
> > accesses a mididevice, which has been created by
> > "snd_seq_device_new(
> ...SNDRV_SEQ_DEV_ID_USBMIDI)".
> > this does not happen here now.
> 
> Autoloading happens if there is an alias for
> snd-card-x (x derived from
> the client number) in modules.conf, and if the card
> driver calls
> snd_seq_device_new() for the sequencer driver. (BTW:
> there was a bug with
> autoloading sequencer drivers which has been fixed
> yesterday)
mmh, i just checked again my tree: it is current.
I put a line 
"alias snd-card-1 snd-usb-midi" 
(the us-428 is my second card) 
into modules.conf. is it this what you suggest?
unfortunately the autoload still does not happen.
Trying to start the Synth with:
"./startBristol -alsa -audiodev hw:1 -mididev hw:1"
snd-usb-midi is still not loaded and the error message
is:
"ALSA lib rawmidi_hw.c:227:(snd_rawmidi_hw_open) open
/dev/snd/midiC1D0 failed: No such file or directory"
Could somebody please explain, how a specific midi
module gets loaded on a user processes access of an
alsa (raw)midi device ?

Karsten



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Re: help needed on how to autoload snd-usb-midi

[Takashi Iwai]

At Tue, 15 Oct 2002 16:40:56 +0200 (CEST),
karsten wiese wrote:
> 
> Hi,
> 
> I am in the process of updating the tascam us-428
> patch for alsa-current and need some hints:
> formerly the snd-usb-us428 issued 
> "request_module( "snd-usb-midi");"
> to load that module. this doesn't work with
> alsa-current anymore as the snd-usb-audio
> initialisation, which is triggered, conflicts with the
> initialisation of snd-usb-us428.
> thus I deleted that "request_module( "snd-usb-midi");"
> from snd_usb_us428.
> I remember from some Mail on this list, that
> snd-usb-midi  would be autoloaded if a users process
> accesses a mididevice, which has been created by 
> "snd_seq_device_new( ...SNDRV_SEQ_DEV_ID_USBMIDI)".
> this does not happen here now.
> what do I miss?
> for the tests I use the bristolsynth with
> "./startBristol -alsa -audiodev hw:1 -mididev hw:1"
> having issued "modprobe snd-usb-midi" before,
> everythingg works as expected. otherwise 
> "Could not open the MIDI interface.
> Error opening midi device hw:1, exiting midi thread"

does support bristrol ALSA sequencer?
if it accesses only the midi device, then snd-usb-midi module won't be
loaded automatically, because the midi device itself is not the
sequencer stuff.
the auto-load mechanism works only when the sequencer stuff is
requested.

i think that an easy way is to force to load snd-usb-midi after
snd-usb-audio, such as above command in /etc/modules.conf.


Takashi


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Re: help needed on how to autoload snd-usb-midi

[Clemens Ladisch]

karsten wiese wrote:
> here is the routine that is used in snd-usb-us428:
> ...
> its a copy-change of usb-audio. something wrong here ?

No, it's fine. The problem is elsewhere.

> > IMHO the "best" solution would be to add a quirk to
> > usbaudio.c, (...) (I'm sure I've missed something.
> > :)
> the us-428 audio is very nonstandard:
> it is necessary to know how many frames are just
> recorded to be able to playback without unwanted
> crackles.

I.e. an asynchronous endpoint without frequency feedback? :-(
There isn't a second endpoint in the playback interface?

> furthermore there are the hardware knobs, sliders and lights,
> the digital in switch....

... and I guess those aren't in any way compatible with USB audio mixer
controls.

> > Autoloading happens if there is an alias for
> > snd-card-x (x derived from
> > the client number) in modules.conf, ...
>
> I put a line
> "alias snd-card-1 snd-usb-midi"
> (the us-428 is my second card)
> into modules.conf. is it this what you suggest?

No, the alias should be for the card driver:
  alias snd-card-1 snd-usb-us428

> unfortunately the autoload still does not happen.

Autoloading works for sequencer ports and for "real" rawmidi devices,
but not for rawmidi devices emulated on top of a sequencer port.

Takashi, would it be possible/desirable to change snd_rawmidi_hw_open()
to load sequencer drivers if the card driver is loaded but the rawmidi
device doesn't exist?
Something like:

	if ((fd = open(filename, fmode)) < 0) {
-		snd_card_load(card);
+		card_loaded = snd_card_load(card) == 0; // 0 or 1?
-		if ((fd = open(filename, fmode)) < 0) {
+		fd = open(filename, fmode);
+		if (card_loaded && fd < 0) {
+			load_seq_dev(...); // hw_open, get_client_info ?
+			fd = open(filename, fmode);
+		}
+		if (fd < 0) {
			snd_ctl_close(ctl);
			SYSERR("open %s failed", filename);
			return -errno;
		}
	}


Regards
Clemens



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Re: help needed on how to autoload snd-usb-midi

[Jaroslav Kysela]

On Wed, 16 Oct 2002, Clemens Ladisch wrote:

> karsten wiese wrote:
> > here is the routine that is used in snd-usb-us428:
> > ...
> > its a copy-change of usb-audio. something wrong here ?
> 
> No, it's fine. The problem is elsewhere.
> 
> > > IMHO the "best" solution would be to add a quirk to
> > > usbaudio.c, (...) (I'm sure I've missed something.
> > > :)
> > the us-428 audio is very nonstandard:
> > it is necessary to know how many frames are just
> > recorded to be able to playback without unwanted
> > crackles.
> 
> I.e. an asynchronous endpoint without frequency feedback? :-(
> There isn't a second endpoint in the playback interface?
> 
> > furthermore there are the hardware knobs, sliders and lights,
> > the digital in switch....
> 
> ... and I guess those aren't in any way compatible with USB audio mixer
> controls.
> 
> > > Autoloading happens if there is an alias for
> > > snd-card-x (x derived from
> > > the client number) in modules.conf, ...
> >
> > I put a line
> > "alias snd-card-1 snd-usb-midi"
> > (the us-428 is my second card)
> > into modules.conf. is it this what you suggest?
> 
> No, the alias should be for the card driver:
>   alias snd-card-1 snd-usb-us428
> 
> > unfortunately the autoload still does not happen.
> 
> Autoloading works for sequencer ports and for "real" rawmidi devices,
> but not for rawmidi devices emulated on top of a sequencer port.
> 
> Takashi, would it be possible/desirable to change snd_rawmidi_hw_open()
> to load sequencer drivers if the card driver is loaded but the rawmidi
> device doesn't exist?
> Something like:
> 
> 	if ((fd = open(filename, fmode)) < 0) {
> -		snd_card_load(card);
> +		card_loaded = snd_card_load(card) == 0; // 0 or 1?
> -		if ((fd = open(filename, fmode)) < 0) {
> +		fd = open(filename, fmode);
> +		if (card_loaded && fd < 0) {
> +			load_seq_dev(...); // hw_open, get_client_info ?
> +			fd = open(filename, fmode);
> +		}
> +		if (fd < 0) {
> 			snd_ctl_close(ctl);
> 			SYSERR("open %s failed", filename);
> 			return -errno;
> 		}
> 	}

It looks ugly. Wouldn't be better to create a direct rawmidi USB driver?
Could you remind me reason, why you parse sequencer events? There's
something special for USB?

						Jaroslav

-----
Jaroslav Kysela <perex@suse.cz>
Linux Kernel Sound Maintainer
ALSA Project  http://www.alsa-project.org
SuSE Linux    http://www.suse.com



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Re: help needed on how to autoload snd-usb-midi

[Clemens Ladisch]

Jaroslav Kysela wrote:
> On Wed, 16 Oct 2002, Clemens Ladisch wrote:
> > Takashi, would it be possible/desirable to change snd_rawmidi_hw_open()
> > to load sequencer drivers if the card driver is loaded but the rawmidi
> > device doesn't exist?
> > Something like:
> > (...)
>
> It looks ugly.

Yes.

> Wouldn't be better to create a direct rawmidi USB driver?
> Could you remind me reason, why you parse sequencer events? There's
> something special for USB?

USB MIDI is not the same as rawmidi as each MIDI command must be sent as a
32-bit packet, so the driver must parse the stream somehow. (There is a
USB MIDI code to send a raw MIDI byte, but there are devices not
supporting this. (The USB MIDI specification and said device are, of
course, from the same company.))

Well, the real reason why I wrote a sequencer driver was that I wanted to
decide between a rawmidi and a sequencer driver, but there wasn't any
sequencer driver supporting input, so I had to write one to find out about
it.  ;-)

It turns out there isn't any real advantage over a rawmidi driver, so I
think I'll change the driver to use rawmidi in the next few days.


Regards
Clemens



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Re: help needed on how to autoload snd-usb-midi

[Peter L Jones]

On Wednesday 16 Oct 2002 12:19, Clemens Ladisch wrote:
[snip]
>
> Well, the real reason why I wrote a sequencer driver was that I wanted to
> decide between a rawmidi and a sequencer driver, but there wasn't any
> sequencer driver supporting input, so I had to write one to find out about
> it.  ;-)

That's a _good_ reason in my book... ;-)

>
> It turns out there isn't any real advantage over a rawmidi driver, so I
> think I'll change the driver to use rawmidi in the next few days.

Will this affect the code used when I'm playing (with) my USB MIDI keyboard?  
(i.e. do I need to test it? ;-) )
>
>
> Regards
> Clemens
>
>
>
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-- Peter


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us428 patch 0.0.4

[karsten wiese]

[-- Attachment #1: Type: text/plain, Size: 1330 bytes --]

hi, this is the logentry:
>>>
compiles again with alsa-current.
USB_ISO_ASAP not used anymore (most of the time),
instead
urb->start_frame is calculated here now, some calls
inside usb-driver don't need to happen anymore.

To get the best out of this:
Disable APM-support in the kernel as APM-BIOS calls
(once each second) hard disable interrupt for many
precious milliseconds.
This helped me much on my slowish PII 400 & PIII 500.
ACPI yet untested but might cause the same bad
behaviour.
Use a kernel with lowlatency and preemptiv patches
applied.
To autoload snd-usb-midi append a line 
	post-install snd-usb-us428 modprobe snd-usb-midi
to /etc/modules.conf.

known problems:
(1) interrupts > 1000 every 1 s.
(2)sliders, knobs, lights not yet handled except
MASTER Volume slider.
(3)"pcm -c 2" doesn't work. "pcm -c 2 -m
direct_interleaved" does.
(4)KDE3.03: "Enable full duplex operation" deadlocks.
<<<


tascams (still unauthorized) firmware is not included
but can be optained off
http://hal9000.drehmoment.org/tascam/

thanks for your support ! 
aaand   does anybody have some clue(s) about the known
problem (3)?

best regards,
karsten




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[-- Attachment #2: us428_0.0.4_alsa0.9_gpl.tar.bz2 --]
[-- Type: application/octet-stream, Size: 18377 bytes --]

Re: help needed on how to autoload snd-usb-midi

[Clemens Ladisch]

Peter L Jones wrote:
> On Wednesday 16 Oct 2002 12:19, Clemens Ladisch wrote:
> > It turns out there isn't any real advantage over a rawmidi driver, so I
> > think I'll change the driver to use rawmidi in the next few days.
>
> Will this affect the code used when I'm playing (with) my USB MIDI keyboard?
> (i.e. do I need to test it? ;-) )

In theory, no.
(In theory, there is no difference between theory and practice. :-)


Regards
Clemens



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