CODEWITHSUNDEEP
linux-device-driver
Michael Zhang
Michael Zhang

Reputation: 81

usb serial driver and ATE1 E0

I am writing an USB serial adapter device driver. The kernel is 3.17.4. The driver works fine except that the kernel opens the adapter twice and writes some commands when the adapter is plugged in. Here are dump_stack() for the driver's open() and write().

1st open() and write(). The kernel writes "ATE1 E0" three times.

<4>[19964.897631] Call Trace:
<4>[19964.897642]  [<ffffffff8173f929>] dump_stack+0x45/0x56
<4>[19964.897649]  [<ffffffffa04aa1ef>] c0087_open+0x2f/0x160    [usb_com_1p_driver]
<4>[19964.897654]  [<ffffffff81744bb2>] ? down_write+0x12/0x40
<4>[19964.897661]  [<ffffffff81566f75>] serial_port_activate+0x65/0x90
<4>[19964.897667]  [<ffffffff8145e864>] ? tty_port_tty_set+0x64/0xa0
<4>[19964.897671]  [<ffffffff8145edf9>] tty_port_open+0x89/0xe0
<4>[19964.897675]  [<ffffffff81567bf3>] serial_open+0x33/0x70
<4>[19964.897679]  [<ffffffff814560eb>] tty_open+0x17b/0x700
<4>[19964.897684]  [<ffffffff8149cf72>] ? kobj_lookup+0x112/0x170
<4>[19964.897690]  [<ffffffff81211017>] chrdev_open+0xb7/0x1a0
<4>[19964.897694]  [<ffffffff81210f60>] ? cdev_put+0x30/0x30
<4>[19964.897698]  [<ffffffff81209832>] do_dentry_open+0x1d2/0x320
<4>[19964.897702]  [<ffffffff81209b61>] finish_open+0x31/0x50
<4>[19964.897706]  [<ffffffff8121cd7c>] do_last+0xc0c/0x11d0
<4>[19964.897710]  [<ffffffff81217bd8>] ? inode_permission+0x18/0x50
<4>[19964.897713]  [<ffffffff812180e9>] ? link_path_walk+0x99/0xee0
<4>[19964.897717]  [<ffffffff8121d40b>] path_openat+0xcb/0x6d0
<4>[19964.897722]  [<ffffffff8121e2ad>] do_filp_open+0x4d/0xc0
<4>[19964.897726]  [<ffffffff812178db>] ? getname_flags+0x4b/0x180
<4>[19964.897731]  [<ffffffff8122b01e>] ? __alloc_fd+0x7e/0x120
<4>[19964.897735]  [<ffffffff8120b61b>] do_sys_open+0x13b/0x250
<4>[19964.897738]  [<ffffffff8120b74e>] SyS_open+0x1e/0x20
<4>[19964.897743]  [<ffffffff81746ae9>] system_call_fastpath+0x16/0x1b


<4>[19965.026562]  [<ffffffff8173f929>] dump_stack+0x45/0x56
<4>[19965.026569]  [<ffffffffa04aa094>] c0087_write+0x24/0x100 [usb_com_1p_driver]
<4>[19965.026575]  [<ffffffff81567890>] serial_write+0x50/0xc0
<4>[19965.026581]  [<ffffffff814584e5>] n_tty_write+0x495/0x560
<4>[19965.026586]  [<ffffffff810c2850>] ? wake_up_state+0x20/0x20
<4>[19965.026590]  [<ffffffff81454a04>] tty_write+0x174/0x300
<4>[19965.026594]  [<ffffffff81458050>] ? process_echoes+0x70/0x70
<4>[19965.026599]  [<ffffffff8120c597>] vfs_write+0xb7/0x1f0
<4>[19965.026603]  [<ffffffff8120d1c5>] SyS_write+0x55/0xd0
<4>[19965.026608]  [<ffffffff81746ae9>] system_call_fastpath+0x16/0x1b

2nd open() and write(). The kernel writes "7e 0 78 f0 7e" twice.

<4>[19977.011908] Call Trace:
<4>[19977.011918]  [<ffffffff8173f929>] dump_stack+0x45/0x56
<4>[19977.011925]  [<ffffffffa04aa1ef>] c0087_open+0x2f/0x160 [usb_com_1p_driver]
<4>[19977.011930]  [<ffffffff81744bb2>] ? down_write+0x12/0x40
<4>[19977.011936]  [<ffffffff81566f75>] serial_port_activate+0x65/0x90
<4>[19977.011941]  [<ffffffff8145e864>] ? tty_port_tty_set+0x64/0xa0
<4>[19977.011945]  [<ffffffff8145edf9>] tty_port_open+0x89/0xe0
<4>[19977.011949]  [<ffffffff81567bf3>] serial_open+0x33/0x70
<4>[19977.011952]  [<ffffffff814560eb>] tty_open+0x17b/0x700
<4>[19977.011958]  [<ffffffff81211017>] chrdev_open+0xb7/0x1a0
<4>[19977.011961]  [<ffffffff81210f60>] ? cdev_put+0x30/0x30
<4>[19977.011965]  [<ffffffff81209832>] do_dentry_open+0x1d2/0x320
<4>[19977.011968]  [<ffffffff81209b61>] finish_open+0x31/0x50
<4>[19977.011972]  [<ffffffff8121cd7c>] do_last+0xc0c/0x11d0
<4>[19977.011975]  [<ffffffff81217bd8>] ? inode_permission+0x18/0x50
<4>[19977.011979]  [<ffffffff812180e9>] ? link_path_walk+0x99/0xee0
<4>[19977.011983]  [<ffffffff8121d40b>] path_openat+0xcb/0x6d0
<4>[19977.011986]  [<ffffffff81455de0>] ? tty_release+0x4c0/0x650
<4>[19977.011990]  [<ffffffff8121e2ad>] do_filp_open+0x4d/0xc0
<4>[19977.011993]  [<ffffffff812178db>] ? getname_flags+0x4b/0x180
<4>[19977.011998]  [<ffffffff8122b01e>] ? __alloc_fd+0x7e/0x120
<4>[19977.012002]  [<ffffffff8120b61b>] do_sys_open+0x13b/0x250
<4>[19977.012025]  [<ffffffff8120b74e>] SyS_open+0x1e/0x20
<4>[19977.012031]  [<ffffffff81746ae9>] system_call_fastpath+0x16/0x1b



<4>[19977.026758]  [<ffffffff8173f929>] dump_stack+0x45/0x56
<4>[19977.026766]  [<ffffffffa04aa094>] c0087_write+0x24/0x100 [usb_com_1p_driver]
<4>[19977.026772]  [<ffffffff81567890>] serial_write+0x50/0xc0
<4>[19977.026777]  [<ffffffff814584e5>] n_tty_write+0x495/0x560
<4>[19977.026782]  [<ffffffff810c2850>] ? wake_up_state+0x20/0x20
<4>[19977.026786]  [<ffffffff81454a04>] tty_write+0x174/0x300
<4>[19977.026789]  [<ffffffff81458050>] ? process_echoes+0x70/0x70
<4>[19977.026794]  [<ffffffff8120c597>] vfs_write+0xb7/0x1f0
<4>[19977.026797]  [<ffffffff8120d1c5>] SyS_write+0x55/0xd0
<4>[19977.026802]  [<ffffffff81746ae9>] system_call_fastpath+0x16/0x1b

Anybody knows what happens here?

Thanks!

Upvotes: 3

Views: 1283

Answers (2)

shycha
shycha

Reputation: 462

On Ubuntu the following command solves the problem:

sudo stop modemmanager

You can the start it again by:

sudo start modemmanager

Upvotes: 1

Michael Zhang
Michael Zhang

Reputation: 81

It is the ModemManager that sends those commands. After stopping ModemManager there are no more commands to the adapter.

Upvotes: 4

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