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| author |   Marcus Folkesson <marcus.folkesson@gmail.com> | 2011-08-30 13:53:10 +0200 |
|---|---|---|
| committer |   Greg Kroah-Hartman <gregkh@suse.de> | 2011-09-22 15:47:53 -0700 |
| commit | e44aabd649c80e8be16ede3ed3cbff6fb2561ca9 (patch) | |
| tree | dbb84aa155527ad4cb08505c8706301e6fe59e22 /drivers/tty | |
| parent | tty: add a DesignWare 8250 driver (diff) | |
| download | linux-dev-e44aabd649c80e8be16ede3ed3cbff6fb2561ca9.tar.xz linux-dev-e44aabd649c80e8be16ede3ed3cbff6fb2561ca9.zip | |
serial: pxa: work around for errata #20
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>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers/tty')
| -rw-r--r-- | 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 531931c1b250..5c8e3bba6c84 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) |