The am335x UART has an interrupt source called RX timeout. Which is described as 'stale' data in the RX FIFO.
When does the timeout occur? Is it basically, the idle time count as described in technical doc as
19.3.8.1.3.7.1 Time-Out Counter
An RX idle condition is detected when the receiver line (uarti_rx) is high for a time that equals 4x the programmed word length + 12 bits. uarti_rx is sampled midway through each bit.
For sleep mode, the counter is reset when there is activity on uarti_rx.
For the time-out interrupt, the counter counts only when there is data in the RX FIFO, and the count is reset when there is activity on uarti_rx or when the UARTi.UART_RHR register is read.
