On Fri, Sep 08, 2006 at 09:45:14PM -0400, Russell Krayer wrote: > I have two boxes, one ppc based, the other amd64. > I have a LCD display that uses a USB-to-serial interface chip from FTDI. > > On the ppc box, the display does not work. > On the amd box, the display does work. > > I captured the data on each box with usbmon. > I can see a difference in the bulk output data transfers. > > The test program I used prints 4 lines of text to the display. > On the ppc box (the one that does not work), one of the lines does work. > The one line that does work compares exactly with the amd64 box. The rest > do not compare. > > The difference is that some of the data have swapped bytes. For example: > > ppc: c7d441e0 4233378685 S Bo:002:02 -115 26 = 1f160000 3e3e3e54 68697320 > 6973206c 696e6520 313c3c3c 2cf8 > > amd64: ffff81001f96d780 1601517566 S Bo:009:02 -115 26 = 1f160000 3e3e3e54 > 68697320 6973206c 696e6520 313c3c3c f82c > > Notice the last words are byte-swapped. > > Can anyone tell me where I should start looking for the culprit? > I look in /usr/src/linux/drivers/usb and I see a lot of code. > Where to begin?
Your user application that sends the wrong byte stream down to the driver :) The driver works on the byte level, it does not even know how to switch byte ordering around. I'd look at your application program for how it creates the buffer that it sends to the driver. hope this heps, greg k-h ------------------------------------------------------------------------- Using Tomcat but need to do more? Need to support web services, security? Get stuff done quickly with pre-integrated technology to make your job easier Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642 _______________________________________________ Linux-usb-users@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-users
