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Cisco Bug: CSCta38769 - ASA Software I2C Driver Issue Partial Bit Bus Error on ASA5505 and SSC

Last Modified

Nov 09, 2016

Products (1)

  • Cisco ASA 5500-X Series Firewalls

Known Affected Releases


Description (partial)


ASA firmware and software I2C driver Issue that causes partial bit  bus error on ASA5505 and SSC. There is a bug in the I2C driver of both ASA firmware and software image that result in I2C bus corruption and error on every single I2C read transaction. There is an extra clock cycle toggle right before the stop condition for read. The read accesses to memory DIMM 0xAB in BIOS don't show this error but any subsequent I2C device access has this error during normal read operation. This is wrong to have the extra bit on the I2C bus everytime a device is being read causing instability and overhead.


This error happens on every read operation, it leads to instability of the whole I2C bus under heavy traffic. The I2C driver codes is being used first on the ASA5505 firmware and leveraged onto ASA5505 software image, SSC firmware and SSC software resulting in heavy usage of original erroneous code with more instability.
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