The status register 1 (S1) is not writeable, hence we should not write it. In order to clear the RDRF flag we only need to read the data register.

Also, when stressing U-Boot a lot with serial input, an overflow can occur which asserts the S1_OR flag (while not asserting the S1_RDRF flag). To clear this flag we again just need to read the data register, hence add this flag to the abort conditions for the while loop.

Insert a compiler barrier to make sure reading the data register gets executed after reading the status register.

Signed-off-by: Stefan Agner stefan@agner.ch --- drivers/serial/serial_lpuart.c | 9 +++------ 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/drivers/serial/serial_lpuart.c b/drivers/serial/serial_lpuart.c index da5f9a2..96173ca 100644 --- a/drivers/serial/serial_lpuart.c +++ b/drivers/serial/serial_lpuart.c @@ -14,6 +14,7 @@

#define US1_TDRE (1 << 7) #define US1_RDRF (1 << 5) +#define US1_OR (1 << 3) #define UC2_TE (1 << 3) #define UC2_RE (1 << 2)

@@ -38,14 +39,10 @@ static void lpuart_serial_setbrg(void)

static int lpuart_serial_getc(void) { - u8 status; - - while (!(__raw_readb(&base->us1) & US1_RDRF)) + while (!(__raw_readb(&base->us1) & (US1_RDRF | US1_OR))) WATCHDOG_RESET();

- status = __raw_readb(&base->us1); - status |= US1_RDRF; - __raw_writeb(status, &base->us1); + barrier();

return __raw_readb(&base->ud); }