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List:       libftdi
Subject:    BUG: CBUS Bitbang Mode Breaks the ftdi_set_baudrate function
From:       Logan Gunthorpe <logang () deltatee ! com>
Date:       2010-03-30 16:23:55
Message-ID: 4BB2259B.6030703 () deltatee ! com
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Hi,

I've found a bug which has been introduced into libftdi 0.17. The bug 
did not exist in 0.16.

I'm using a FT232R as a serial port with the CBUS in bit bang mode.

The problem is after configuring the CBUS with ftdi_set_bitmode, I can 
no longer set the baudrate correctly.

I believe the bug is on the second last line of the ftdi_set_bitmode 
function. In 0.17 it is:

ftdi->bitbang_enabled = (mode == BITMODE_RESET) ? 0 : 1;

In 0.16 it is:

ftdi->bitbang_enabled = (mode == BITMODE_BITBANG || mode == 
BITMODE_SYNCBB)?1:0;

The ftdi->bitbang_enabled flag appears to cause the baudrate set to be 
multiplied by 4. Therefore, in 0.16 when the mode is BITMODE_CBUS the 
flag is not set and setting the baudrate functions correctly. In 0.17 
the flag gets set and the baudrate can no longer be changed without 
dividing it by 4 first.

I'm not sure about the other bit bang modes, but perhaps this change 
should be revisited.

Thanks,

Logan

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