Some platforms (e.g. IGEPv2 board) has a broken ns16550 UART that does not set the TEMT bit when the transmitter is empty in SPL. This makes U-Boot to hang while waiting for TEMT to be set.
Add a new option to avoid this:
CONFIG_SYS_NS16550_BROKEN_TEMT
16550 UART set the Transmitter Empty (TEMT) Bit when all output has finished and the transmitter is totally empty. U-Boot waits for this bit to be set to initialize the serial console. On some broken platforms this bit is not set in SPL making U-Boot to hang while waiting for TEMT. Define this option to avoid it.
Signed-off-by: Javier Martinez Canillas javier.martinez@collabora.co.uk --- README | 8 ++++++++ drivers/serial/ns16550.c | 2 ++ 2 files changed, 10 insertions(+), 0 deletions(-)
diff --git a/README b/README index 78f40df..a89861e 100644 --- a/README +++ b/README @@ -616,6 +616,14 @@ The following options need to be configured: boot loader that has already initialized the UART. Define this variable to flush the UART at init time.
+ CONFIG_SYS_NS16550_BROKEN_TEMT + + 16550 UART set the Transmitter Empty (TEMT) Bit when all output + has finished and the transmitter is totally empty. U-Boot waits + for this bit to be set to initialize the serial console. On some + broken platforms this bit is not set in SPL making U-Boot to + hang while waiting for TEMT. Define this option to avoid it. +
- Console Interface: Depending on board, define exactly one serial port diff --git a/drivers/serial/ns16550.c b/drivers/serial/ns16550.c index bbd91ca..87a0917 100644 --- a/drivers/serial/ns16550.c +++ b/drivers/serial/ns16550.c @@ -36,8 +36,10 @@
void NS16550_init(NS16550_t com_port, int baud_divisor) { +#if (!defined(CONFIG_SYS_NS16550_BROKEN_TEMT)) while (!(serial_in(&com_port->lsr) & UART_LSR_TEMT)) ; +#endif
serial_out(CONFIG_SYS_NS16550_IER, &com_port->ier); #if (defined(CONFIG_OMAP) && !defined(CONFIG_OMAP3_ZOOM2)) || \