On 07/28/2016 08:54 PM, Stefan Sauer wrote:
> On 07/28/2016 01:27 PM, Clemens Ladisch wrote:
>> Stefan Sauer wrote:
>>> Another weir issue is that once the usb connection is established,
>>> playing the synth from its own knobs and keys is super sluggish (e.g. a
>>> key release is recognized with a multi-second delay).
>> Apparently, the firmware waits for the PC to read the MIDI messages.
>> Which the Linux driver does not do until a MIDI port is actually opened,
>> in order to save a little bit of power. Oh well, I'll have to change
>> this back.
> If you can point me to the change I can locally test if that fixes it. I
> just rebuilt my kernel and locally applied
> http://git.kernel.org/cgit/linux/kernel/git/tiwai/sound.git/commit/?id=ae7cc709f2ec11b49fc31b20cd8c943794ae9576
> which is only in Takashis branch, but not in the mainline. It does not
> seem seem to have any visiible effect though.
> Am I right to assume that the quirks-table.h ends up in snd-usb-audio.ko
> ? Because I only updated this mod.
My bad, you removed the quirks entry in
http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=8e5ced83dd1c3090c96c4e0614703f0f2a5ba2f4
So they don't seems to be needed anymore.
> Any idea what I could try to figure out why the incomming audio is silent?
>>> One detail is that when connecting the synth to usb I get several
>>> "[159320.243035] usb 4-1.5: Unable to change format on ep #84: already
>>> in use" messages in syslog.
>> This is another driver bug. The exact cause is not known, and nobody
>> has fixed it yet due to lack of time.
> This is from ./sound/usb/endpoint.c:811:
> I am really just guessing, but could this be related to that these
> devices run both an audio and a midi interface on the same usb connection?
This sees to be causing the silent input audio, endpoint 84 might be the
audio-in
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 1
bAlternateSetting 1
bNumEndpoints 1
bInterfaceClass 255 Vendor Specific Class
bInterfaceSubClass 2
bInterfaceProtocol 1
iInterface 0
** UNRECOGNIZED: 07 24 01 07 00 01 00
** UNRECOGNIZED: 0b 24 02 01 02 04 18 01 44 ac 00
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x84 EP 4 IN
bmAttributes 37
Transfer Type Isochronous
Synch Type Asynchronous
Usage Type Implicit feedback Data
wMaxPacketSize 0x0070 1x 112 bytes
bInterval 1
Stefan
>
> Stefan
>>
>> Regards,
>> Clemens
>
>
>
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