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

[Tom]

Grazvydas Ignotas wrote:
> 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).

Good.
Please add this comment to the commit log.
Please also add a similar comment to the code.

The mux code is cyptic, documenting helps.
Tom

> 
>> 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