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On May 17, 2006, at 5:14 AM, Zang Roy-r61911 wrote:

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This patch contains changes to the serial device driver 

specific for 

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integrated serial port in Tsi108 Host Bridge.

There's no explaination about why this is required.  What is 
the problem?
Which changes relate directly to this problem and which 
changes are related to fixing some other issue not related to 
the errata?

More detailed explanation:

This patch addresses two differences in the Tsi108/109 UART behavior from the standard one.

1. Check for UART_IER_UUE bit in the autoconfig routine. This section of autoconfig is excluded for 
Tsi108/109 because bits 7 and 6 are reserved for internal use. They are R/W bits. In addition to incorrect
 identification, changing these bits (from 00) will make Tsi108/109 UART non-functional.  

2. ERRATA. Reading the UART's Interrupt Identification Register (IIR) clears the Transmit 
Holding Register Empty (THRE) and Transmit buffer Empty (TEMP) interrupts even 
if they are not enabled in the Interrupt Enable Register (IER). This leads to loss of the interrupts. 
Interrupts are not cleared when reading UART registers as 32-bit word.