[U-Boot] [PATCH 1/2] serial/ns16550: add an option to avoid hanging on broken platforms

[U-Boot] [PATCH 1/2] serial/ns16550: add an option to avoid hanging on broken platforms

[Javier Martinez Canillas]

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)) || \
-- 
1.7.7.6

[U-Boot] [PATCH 2/2] OMAP3: igep00x0: add CONFIG_SYS_NS16550_BROKEN_TEMT

[Javier Martinez Canillas]

IGEP board PC16550D (ns16550) UART doesn't set the
Transmitter Empty (TEMT) Bit in SPL. This makes
U-Boot to hang while waiting for TEMT. Add the
CONFIG_SYS_NS16550_BROKEN_TEMT config option to
avoid this issue.

Signed-off-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
---
 include/configs/igep00x0.h |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/include/configs/igep00x0.h b/include/configs/igep00x0.h
index 2110e64..a5912f0 100644
--- a/include/configs/igep00x0.h
+++ b/include/configs/igep00x0.h
@@ -67,6 +67,9 @@
 #define CONFIG_SYS_NS16550_REG_SIZE	(-4)
 #define CONFIG_SYS_NS16550_CLK		V_NS16550_CLK
 
+/* define to avoid U-Boot to hang while waiting for TEMT */
+#define CONFIG_SYS_NS16550_BROKEN_TEMT
+
 /* select serial console configuration */
 #define CONFIG_CONS_INDEX		3
 #define CONFIG_SYS_NS16550_COM3		OMAP34XX_UART3
-- 
1.7.7.6

[U-Boot] [U-Boot, 1/2] serial/ns16550: add an option to avoid hanging on broken platforms

[Tom Rini]

On Mon, Jan 07, 2013 at 01:35:20AM -0000, Javier Martinez Canillas wrote:

> 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>

Applied to u-boot-ti/master, thanks!

-- 
Tom
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[U-Boot] [U-Boot, 2/2] OMAP3: igep00x0: add CONFIG_SYS_NS16550_BROKEN_TEMT

[Tom Rini]

On Mon, Jan 07, 2013 at 01:35:21AM -0000, Javier Martinez Canillas wrote:

> IGEP board PC16550D (ns16550) UART doesn't set the
> Transmitter Empty (TEMT) Bit in SPL. This makes
> U-Boot to hang while waiting for TEMT. Add the
> CONFIG_SYS_NS16550_BROKEN_TEMT config option to
> avoid this issue.
> 
> Signed-off-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>

Applied to u-boot-ti/master, thanks!

-- 
Tom
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