[alsa-devel] How to add a new MIDI device to the usbaudio driver

[Kristian Amlie]

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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