From: Marcus Folkesson Date: Tue, 30 Aug 2011 11:53:10 +0000 (+0200) Subject: serial: pxa: work around for errata #20 X-Git-Tag: v3.0.9~250 X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=d5fe5d1648b88aa16b5d97d088d9b743bc9ce0a8;p=karo-tx-linux.git serial: pxa: work around for errata #20 commit e44aabd649c80e8be16ede3ed3cbff6fb2561ca9 upstream. Errata E20: UART: Character Timeout interrupt remains set under certain software conditions. Implication: The software servicing the UART can be trapped in an infinite loop. Signed-off-by: Marcus Folkesson Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/tty/serial/pxa.c b/drivers/tty/serial/pxa.c index 4302e6e3768e..81243a62dd59 100644 --- a/drivers/tty/serial/pxa.c +++ b/drivers/tty/serial/pxa.c @@ -100,6 +100,16 @@ static inline void receive_chars(struct uart_pxa_port *up, int *status) int max_count = 256; do { + /* work around Errata #20 according to + * Intel(R) PXA27x Processor Family + * Specification Update (May 2005) + * + * Step 2 + * Disable the Reciever Time Out Interrupt via IER[RTOEI] + */ + up->ier &= ~UART_IER_RTOIE; + serial_out(up, UART_IER, up->ier); + ch = serial_in(up, UART_RX); flag = TTY_NORMAL; up->port.icount.rx++; @@ -156,6 +166,16 @@ static inline void receive_chars(struct uart_pxa_port *up, int *status) *status = serial_in(up, UART_LSR); } while ((*status & UART_LSR_DR) && (max_count-- > 0)); tty_flip_buffer_push(tty); + + /* work around Errata #20 according to + * Intel(R) PXA27x Processor Family + * Specification Update (May 2005) + * + * Step 6: + * No more data in FIFO: Re-enable RTO interrupt via IER[RTOIE] + */ + up->ier |= UART_IER_RTOIE; + serial_out(up, UART_IER, up->ier); } static void transmit_chars(struct uart_pxa_port *up)