[PATCH] serial: pxa: work around for errata #20
From: marcus.folkesson@gmail.com
Date: 2011-08-30 11:53:43
Also in:
lkml
Subsystem:
the rest, tty layer and serial drivers · Maintainers:
Linus Torvalds, Greg Kroah-Hartman, Jiri Slaby
Possibly related (same subject, not in this thread)
- 2011-07-30 · [PATCH] serial: pxa: work around for errata #20 · Marcus Folkesson <marcus.folkesson@gmail.com>
From: Marcus Folkesson <marcus.folkesson@gmail.com> 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 <marcus.folkesson@gmail.com> --- drivers/tty/serial/pxa.c | 20 ++++++++++++++++++++ 1 files changed, 20 insertions(+), 0 deletions(-)
diff --git a/drivers/tty/serial/pxa.c b/drivers/tty/serial/pxa.c
index 531931c..5c8e3bb 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)
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1.7.4.1