Re: How to add a new MIDI device to the usbaudio driver

[Kristian Amlie <kristian@amlie.name>]

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On 08/24/11 10:32, Daniel Mack wrote:
> Hmm? Can you trace where this happens and which dereferenced pointer
> is NULL? I don't see it, sorry.

The attached patch solves the NULL pointer dereference. With this patch,
the device shows up as a MIDI device, but still produces no events
according to aseqdump.

I did a more thorough examination of the calls to usb_control_msg() from
the ftdi_sio driver, and this is what I came up with:

Plugging it in:

Calling usb_control_msg() from read_latency_timer(): value=0, index=0
Calling usb_control_msg() from write_latency_timer(): value=1, index=0
usb 3-2: FTDI USB Serial Device converter now attached to ttyUSB0

Starting cu:

Calling usb_control_msg() from ftdi_open(): value=0, index=0
Calling usb_control_msg() from ftdi_set_termios(): value=8, index=0
Calling usb_control_msg() from change_speed(): value=16696, index=0
Calling usb_control_msg() from ftdi_set_termios(): value=0, index=0
Calling usb_control_msg() from update_mctrl(): value=771, index=0
Calling usb_control_msg() from ftdi_set_termios(): value=8, index=0
Calling usb_control_msg() from change_speed(): value=49230, index=0
Calling usb_control_msg() from ftdi_set_termios(): value=0, index=0
Calling usb_control_msg() from ftdi_set_termios(): value=8, index=0
Calling usb_control_msg() from change_speed(): value=49230, index=0
Calling usb_control_msg() from ftdi_set_termios(): value=0, index=0
Calling usb_control_msg() from ftdi_set_termios(): value=8, index=0
Calling usb_control_msg() from change_speed(): value=49230, index=0
Calling usb_control_msg() from ftdi_set_termios(): value=4881, index=1024

Killing cu:

Calling usb_control_msg() from ftdi_set_termios(): value=8, index=0
Calling usb_control_msg() from change_speed(): value=16696, index=0
Calling usb_control_msg() from ftdi_set_termios(): value=0, index=0
Calling usb_control_msg() from ftdi_dtr_rts(): value=0, index=0
Calling usb_control_msg() from update_mctrl(): value=768, index=0

-- 
Kristian

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diff --git a/sound/usb/quirks.c b/sound/usb/quirks.c
index 090e193..65591df 100644
--- a/sound/usb/quirks.c
+++ b/sound/usb/quirks.c
@@ -306,6 +306,7 @@ int snd_usb_create_quirk(struct snd_usb_audio *chip,
 		[QUIRK_MIDI_EMAGIC] = create_any_midi_quirk,
 		[QUIRK_MIDI_CME] = create_any_midi_quirk,
 		[QUIRK_MIDI_AKAI] = create_any_midi_quirk,
+		[QUIRK_MIDI_FTDI] = create_any_midi_quirk,
 		[QUIRK_AUDIO_STANDARD_INTERFACE] = create_standard_audio_quirk,
 		[QUIRK_AUDIO_FIXED_ENDPOINT] = create_fixed_stream_quirk,
 		[QUIRK_AUDIO_EDIROL_UAXX] = create_uaxx_quirk,

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