Oliver Neukum wrote:
> Am Montag, 4. Februar 2008 09:58:19 schrieb Clemens Ladisch:
>> Oliver Neukum wrote:
>> > this patch implements autosuspend for USB audio devices.
>>
>> The Creative Audigy 2 NX mutes itself when being suspended but doesn't
>> unmute when resuming. (Apparently, this self-powered device treats
>> supend the same as disconnection.)
>
> It must be added to the USB quirk list. Please provide vendor:product id.
>
>> The Roland SC-8820 resets itself when being resumed and loses all
>
> A quirk is needed, too.

/* Creative SB Audigy 2 NX */
USB_DEVICE(0x041e, 0x3020)
/* Roland SC-8820 */
USB_DEVICE(0x0582, 0x0007)
/* Edirol SD-20 */
USB_DEVICE(0x0582, 0x0027)

I fear there are many other devices with similar problems.

>> parameter settings.  Furthermore, it should be possible to use this
>> device with its external input even when the computer isn't accessing
>> it.
>
> How could the device be used without the computer? Please explain.

It's a MIDI synthesizer with an external MIDI input.  It's possible to
connect a MIDI keyboard directly and to use the computer just for power
and/or for setting parameters before playing.

>> The Edirol UA-1A resumes OK (but it doesn't have any internal state).
>
> Not even volume? Mute/unmute?

No.

>> Your patch doesn't touch usbmidi.c -- USB MIDI devices are suspended
>> even when they're being used.
>
> Yes, I noticed. I thought midi is a separate driver. Is there documentation
> on the midi API?

Documentation/DocBook/writing-an-alsa-driver, section
"RawMIDI Interface".

Just use the *_open/*_close and *_disconnect callbacks.


Regards,
Clemens
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