[U-Boot] [PATCH] OMAP3: pandora: fix booting without serial attached

[Grazvydas Ignotas]

On Wed, Nov 11, 2009 at 11:14 PM, Tom <Tom.Rix at windriver.com> wrote:
> Grazvydas Ignotas wrote:
>>
>> When the board is booted without serial cable attached (which
>> is how most of them will be used) UART RX is left floating and
>> sometimes picks noise, which interrupts countdown and enters
>> U-Boot prompt instead of booting the kernel. Fix this by setting
>> up internal pullup on UART RX pin.
>>
>> Signed-off-by: Grazvydas Ignotas <notasas at gmail.com>
>> ---
>>  board/pandora/pandora.h |    2 +-
>>  1 files changed, 1 insertions(+), 1 deletions(-)
>>
>> diff --git a/board/pandora/pandora.h b/board/pandora/pandora.h
>> index 5bfa0f9..f1e1db9 100644
>> --- a/board/pandora/pandora.h
>> +++ b/board/pandora/pandora.h
>> @@ -219,7 +219,7 @@ const omap3_sysinfo sysinfo = {
>>        MUX_VAL(CP(UART2_RX),           (IEN  | PTD | EN  | M4))
>> /*GPIO_147,*/\
>>
>> /*UART2_RX*/\
>>  /*Serial Interface (Peripheral boot, Linux console, on AV connector)*/\
>> -       MUX_VAL(CP(UART3_RX_IRRX),      (IEN  | PTD | DIS | M0))
>> /*UART3_RX*/\
>> +       MUX_VAL(CP(UART3_RX_IRRX),      (IEN  | PTU | EN  | M0))
>> /*UART3_RX*/\
>>        MUX_VAL(CP(UART3_TX_IRTX),      (IDIS | PTD | DIS | M0))
>> /*UART3_TX*/\
>>  /*LEDs (Controlled by OMAP)*/\
>>        MUX_VAL(CP(MMC1_DAT6),          (IDIS | PTD | DIS | M4))
>> /*GPIO_128*/\
>
> Will this change disable normal u-boot serial?

No it won't, it only enables weak internal pullup resistor in OMAP,
which won't prevent the UART from working, only pull it up when
nothing is driving the pin (i.e. cable not conneted).

> From the config file
>
> /*
>  * select serial console configuration
>  */
> #define CONFIG_CONS_INDEX               3
> #define CONFIG_SYS_NS16550_COM3         OMAP34XX_UART3
> #define CONFIG_SERIAL3                  3
>
> It looks like it will.
>
> This must be as a non default config option.
>
> Tom