[BUG] usb-serial / pl2302 corrupted receive

From: Peter Feuerer
Date: Mon Mar 01 2010 - 13:09:57 EST

Hi Greg,

I tried to flash an AVR microcontroler via an USB to serial converter which uses pl2302 driver. It didn't work, so I set up following test to reproduce the bug:

I connected two pls2302 usb-serial converters to two different usb-ports of my machine and connected them with a rs232-nullmodem cable to each other.

cat /dev/ttyUSB1

while true; do echo 123456789012345678901234567890 > /dev/ttyUSB0 ; done

When both usb-serial converters are plugged in, the first few lines appear correctly on Terminal1. Then I noticed two different bahaviors:

1) The lines on Terminal1 are corrupted like: "1111111111111111111111123456789012345678901234567890"

2) The lines "123456789012345678901234567890" appear correctly on Terminal1 but when I kill the "cat" command and start it again, there's only one line and then no output anymore.

I verified this behavior on two different machines running the same kernel (version

Additionally a calltrace is printed to dmesg (see end of mail)

I'm not 100% sure, but if I remember correctly was flashing AVR microcontrollers with pl2302 possible about the time when kernel 2.6.22 was released.

If you've got any questions I'd be pleased to help you.

best regards,

[piie@deskpiie ~]$ lsusb
Bus 002 Device 013: ID 067b:2303 Prolific Technology, Inc. PL2303 Serial Port
Bus 002 Device 012: ID 067b:2303 Prolific Technology, Inc. PL2303 Serial Port

------------[ cut here ]------------
WARNING: at drivers/usb/serial/usb-serial.c:406 serial_write_room+0x74/0x80 [usbserial]()
Hardware name: To Be Filled By O.E.M.
Modules linked in: pl2303 usbserial sha256_generic aes_i586 aes_generic cbc ipv6 snd_hda_codec_nvhdmi usbhid hid snd_hda_codec_via snd_seq_dummy snd_seq_oss snd_seq_midi_event snd_seq snd_seq_device snd_pcm_oss snd_mixer_oss snd_hda_intel snd_hda_codec snd_hwdep snd_pcm snd_timer ohci_hcd snd soundcore coretemp snd_page_alloc nvidia(P) shpchp i2c_nforce2 ehci_hcd agpgart wmi psmouse thermal pci_hotplug i2c_core usbcore sg forcedeth button processor serio_raw vboxdrv evdev dm_crypt dm_mod fuse rtc_cmos rtc_core rtc_lib ext4 mbcache jbd2 crc16 sr_mod cdrom sd_mod pata_acpi ahci ata_generic libata scsi_mod
Pid: 15, comm: events/0 Tainted: P W 2.6.32-ARCH #1
Call Trace:
[<c104042e>] ? warn_slowpath_common+0x6e/0xb0
[<f8c634b4>] ? serial_write_room+0x74/0x80 [usbserial]
[<c1040483>] ? warn_slowpath_null+0x13/0x20
[<f8c634b4>] ? serial_write_room+0x74/0x80 [usbserial]
[<c11ddf15>] ? tty_write_room+0x15/0x20
[<c11db6a7>] ? process_echoes+0x47/0x2b0
[<c11dda85>] ? n_tty_receive_buf+0xe45/0x10c0
[<c1002374>] ? __switch_to+0x184/0x190
[<c103655b>] ? finish_task_switch+0x3b/0xa0
[<c12b77d9>] ? schedule+0x2f9/0xa30
[<f8e2cfea>] ? usb_autopm_do_interface+0x7a/0xe0 [usbcore]
[<c11e023a>] ? flush_to_ldisc+0x14a/0x180
[<c11e00f0>] ? flush_to_ldisc+0x0/0x180
[<c1056f7f>] ? worker_thread+0x11f/0x260
[<c105adf0>] ? autoremove_wake_function+0x0/0x40
[<c1056e60>] ? worker_thread+0x0/0x260
[<c105ab44>] ? kthread+0x74/0x80
[<c105aad0>] ? kthread+0x0/0x80
[<c1004627>] ? kernel_thread_helper+0x7/0x10
---[ end trace 4162a861717078f5 ]---
------------[ cut here ]------------

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