CP2102で文字化け

無負荷/低負荷だと問題ないんだけど、Linux側のディスクIOに負荷がかかると文字化ける。
受信ユニット側は、負荷をかけてもちゃんと表示しているので、こちらのファームではなさそうか。
それともFIFOの読み取り時に割り込み待ちが発生すると、へんな動作をしてしまうのか。
送り出し側のソフトのnice値を上げてみても改善しない。
これはドライバかな...
メーカーのドライバの最新はこれ。
http://www.silabs.com/tgwWebApp/public/web_content/products/Microcontrollers/USB/en/mcu_vcp.htm

This release includes drivers for Linux v2.6 and Linux 2.6.10-14.

使っている環境のものとドライバは同じ。

Linux 2.6.12.6-arm1 #2 Mon Jun 18 17:29:41 JST 2007 armv5tejl GNU/Linux

Changelogを追ってみる。

ChangeLog-2.6.14
commit 198b95170f2c7ad56b4ba92fe3d4d896f5be5c7e
Author: Craig Shelley
Date: Sun Aug 28 09:51:15 2005 +0100
[PATCH] USB: CP2101 New Device IDs
Three new device IDs for CP2101 USB to UART Bridge

ChangeLog-2.6.15
commit b0ce84d5539de88a1001f9aa3deeaa20fde3d152
Author: Josef Balatka
Date: Thu Nov 17 09:47:24 2005 -0800
[PATCH] USB: cp2101.c: Jablotron usb serial interface identification
Jablotron usb serial interface identification

ChangeLog-2.6.16
commit e988fc8a56bb3f76624dd7b0fb13ae3eaccefa59
Author: Craig Shelley
Date: Fri Jan 20 00:06:19 2006 +0000
[PATCH] USB: cp2101 Add new device IDs
The attached patch adds four new device IDs for the CP2101 driver.
Also 3 tab characters have been removed from device ID table.

ChangeLog-2.6.17
commit 59224f5352542b968c41200954e56c26c4f0a075
Author: Craig Shelley
Date: Sat Mar 11 11:29:02 2006 +0000
[PATCH] USB: cp2101: add new device IDs
This patch adds a new device ID to the cp2101 driver

ChangeLog-2.6.18
commit 212a4b4ed1ea9a969f3f967b3e3a8075ad1cb4de
Author: Vitja Makarov
Date: Wed May 31 00:40:06 2006 +0400
[PATCH] USB: new cp2101 device
By the way I have to ask you to add new (vid,pid) pair to cp2101 driver.
This device is argussoft's avr in-system programmer AS3M,
http://atmel.argussoft.ru/hard.htm
it's based on cp2101 chip and works pretty well with the linux driver.
It could be used with argussoft's `asisp1109.exe'
(http://atmel.argussoft.ru/download/software/as-tools.soft/asisp.zip)
tool run under wine.

ChangeLog-2.6.19
commit 78001e3d75c5d3ae1e8dc9875892b9461e4c8d4b
Author: Bjorn Schneider
Date: Sat Oct 28 12:42:04 2006 +0200
USB: new VID/PID-combos for cp2101
3 new VID/PID combinations (registered with Silicon Laboratories Inc.)
added for devices made by Lipowsky Industrie Elektronik GmbH all using
the CP2102 usb-to-serial converter (Baby-JTAG, Baby-LIN, HARP-1).
commit 61926b975d83aa6c0124b5b0ce40c08579e6cc98
Author: Craig Shelley
Date: Thu Oct 12 22:09:56 2006 +0100
USB-SERIAL:cp2101 Add new device ID
This patch adds device ID 0xEA61. This is another factory default ID
used by SILabs.

ChangeLog-2.6.20
commit e05998d50d0bf9de5409a178e2f9869c7d1ea83e
Author: Johannes Hoelzl
Date: Sat Dec 2 16:54:27 2006 +0100
Add Baltech Reader ID to CP2101 driver
this patch adds the Baltech Reader ID to the list of USB IDs in the
CP2101 driver.

ChangeLog-2.6.21
commit fc4bd64cbbbea1eabc77d6f1734c0f8fb7e0295f
Author: Jon K Hellan
Date: Wed Feb 28 23:04:33 2007 +0100
USB: New device IDs for cp2101 driver
Here are two new device IDs for the cp2101 driver.
The diff is with linus's tree as of this evending.
commit ebaf494e2ad19c92d3af48feaf9d65fdb656ea28
Author: Pozsar Balazs
Date: Fri Feb 16 12:47:49 2007 +0100
USB: another id for cp2101 driver
This patch adds another usb id to the cp2101. It seems to work well.

ChangeLog-2.6.22
commit 92f5cae2e8914d2d762728dd7629e5121ba070f3
Author: Craig Shelley
Date: Fri Apr 20 14:37:17 2007 +0100
USB: CP2101 New Device IDs
Two new device IDs for CP2101 driver.

IDの追加以外はChangelogには出てこない。
採用するデバイスは増えているようだ。
ドライバ側じゃないとしたら、CPUアーキテクチャとかのハード依存の問題かな... でもUSBだしな。

深みにはまっている感じ。