[U-Boot] No single character output after update to latest u-boot on pandaboard

Lokesh Vutla
2013-11-26T04:40:28Z

Hi,
On Tuesday 26 November 2013 09:55 AM, Abraham V. wrote:
> Hello Chao,
> (cc R.Sricharan from TI)
>
> Quite frankly, I have no idea why your pandaboard fails to work if
> CONFIG_SYS_ENABLE_PADS_ALL isn't defined in the omap4_common.h file. From
> the logs this patch was committed on 13/June/2012 by R.Sricharan. He might
> have a better explanation so I'm adding him to this discussion. The git log
> message says this,
If we enable CONFIG_SYS_ENABLE_PADS_ALL, pin mux for non essential pads for u-boot
will be configured. Ideally this configuration should be taken care by kernel. This is the main reason
to remove this config option.
Due to this reason the following is added to ./doc/feature-removal-schedule.txt

"What: Remove CONFIG_SYS_ENABLE_PADS_ALL and CONFIG_SYS_CLOCKS_ENABLE_ALL
When: Release v2013.07

Why: When set these options enable "all" of the pads and clocks found
on OMAP4/5 platforms, so that the Linux Kernel does not have to.
It has been agreed that this goes against the U-Boot design
philosophy and since f3f98bb0 we have not enabled more than is
used in U-Boot. The kernel has been updating drivers to enable
rather than assume pads/clocks have been enabled already. Our
expectation is that by v2013.07 a suitable kernel shall exist that
does not need these options set for a reasonable I/O set to function.

Who: Tom Rini <trini@ti.com> and Sricharan R <r.sricharan@ti.com>"

Please let me know if I am not clear.

>
> "ARM: OMAP4/5: Do not configure non essential pads, clocks, dplls.
>
> Currently on OMAP4/5 platforms, many kernel drivers are dependent
> upon the bootloaders for mux, dpll and clock configurations.
> This should not be the case and bootloaders should set only the
> minimum required for the uboot functionality and kernel boot.
>
> Note that this is going to break the kernel drivers. But this
> is the only way to get things fixed in the kernel.
>
> Signed-off-by: R Sricharan <r.sricharan@ti.com>"
>
> so I'm curious now. Chao - was your problem that uboot refused to start or
> were you seeing crashes in the linux kernel? If it's the former, then the
> kernel doesn't even come into the picture.
Yes even I am not clear at this point. Chao can you please clarify.
Ideally the above config will not harm U-Boot to come up on your board.

Thanks and regards,
Lokesh
>
> Also, if you could try a simple experiment? Instead of defining that in the
> common file, could you define it in the omap4_panda.h file and tell us if
> uboot comes up? ( I'm just hesitant to make changes to a common file if the
> issue is on only one board)
>
> Puzzled,
> Abraham V.
>
>
> On Tue, Nov 26, 2013 at 9:14 AM, Chao Xu <caesarxuchao@gmail.com> wrote:
>
>> Hi Abraham,
>>
>> I finally got it working by adding "#define
>> CONFIG_SYS_ENABLE_PADS_ALL" in u-boot/include/configs/omap4_common.h!
>> This is removed by default in v2013.10. Do you know why? Thank you!
>>
>> On Sun, Nov 24, 2013 at 10:11 PM, Abraham V.
>> <abraham.varricatt@vvdntech.com> wrote:
>>> Hello Chao,
>>>
>>> That sounds odd. Can you try downloading the latest mainline uboot
>> sources
>>> and compiling those for your board?
>>>
>>> ftp://ftp.denx.de/pub/u-boot/
>>>
>>> At least, for the pandaboard I have, the 2013.10 release works well,
>>> following your instructions. Only difference is that I'm using linaro's
>>> cross-compiler.
>>>
>>> Puzzled,
>>> Abraham V.
>>>
>>>
>>> On Fri, Nov 22, 2013 at 8:59 PM, Chao Xu <caesarxuchao@gmail.com> wrote:
>>>>
>>>> Hi Abraham,
>>>>
>>>> Thank you very much for your detailed reply! But I think I can rule
>>>> out the three possible problems you mentioned.
>>>> 1. The cross compiler should be fine. Because I use it all the time to
>>>> compile kernel for pandaboard and it has never been a problem
>>>> 2. I'm doing exactly what you suggested, i.e. the SD card is
>>>> partitioned by a pre-built image.
>>>> 3. The serial cable is fine because the pre-built image was working
>>>> properly with the serial cable. Only after I update the u-boot comes
>>>> the no-output problem.
>>>> Could you think of any other possible problem? I suspect maybe I need
>>>> to modify other files (uEnv.txt, boot.scr) in the /boot partition?
>>>> These files came along with the pre-built image. Thanks again.
>>>>
>>>> On Fri, Nov 22, 2013 at 3:17 AM, Abraham V.
>>>> <abraham.varricatt@vvdntech.com> wrote:
>>>>> My company is designing a custom board that can be thought of as a
>>>>> derivative of the pandaboard. I believe we have Rev B1 with us in the
>>>>> office.
>>>>>
>>>>> Considering that you are not getting any debug messages on your serial
>>>>> console, I suspect one of the following;
>>>>> * your cross-compiler might have issues
>>>>> * you haven't partitioned the SD card properly
>>>>> * your serial cable might be damaged.
>>>>>
>>>>> Just short the TX and RX lines of your serial cable to test the last
>>>>> point.
>>>>> If you can see echo messages, then good, at least the cable is
>> working.
>>>>>
>>>>> Next worry about the partitions - to boot from SD card, the omap4 on
>> the
>>>>> pandaboard expects it in a certain format. Try using pre-build
>> binaries.
>>>>> For
>>>>> example;
>>>>>
>>>>> http://www.omappedia.com/wiki/Android_Panda_Pre_Built
>>>>> http://omappedia.org/wiki/Ubuntu_Pre-built_Binaries_Guide
>>>>>
>>>>> They have instructions on how to format your SD card. Assuming they
>>>>> work,
>>>>> then good! Last point is to check your cross-compiler. Just replace
>> the
>>>>> existing MLO and u-boot.bin (or u-boot.img; it depends on what version
>>>>> you
>>>>> have) on the SD card with your compiled ones and you'll be in a good
>>>>> position to narrow down bugs.
>>>>>
>>>>> All the best,
>>>>> Abraham V.
>>>>>
>>>>>
>>>>> On Fri, Nov 22, 2013 at 11:41 AM, Chao Xu <caesarxuchao@gmail.com>
>>>>> wrote:
>>>>>>
>>>>>> Hi,
>>>>>>
>>>>>> I'm trying to compile the latest u-boot for my Pandaboard Rev A2. The
>>>>>> SD card was originally loaded with a working version of 12.04
>>>>>> linaro-unbunt-developer image. Early printk is enabled in the
>> original
>>>>>> image.
>>>>>>
>>>>>> I followed this guide (http://elinux.org/Panda_How_to_MLO_%26_u-boot
>> )
>>>>>> and here is what I did:
>>>>>> 1. export ARCH=arm
>>>>>> 2. export CROSS_COMPILE=arm-linux-gnueabi-
>>>>>> 3. make omap4_panda_config
>>>>>> 4.make
>>>>>> 5. cp MLO u-boot.img /SDCARD/boot/
>>>>>>
>>>>>> But when switching on my Panda, there is no output from the serial
>>>>>> port. And the heartbeat LED is always off. (When every thing works,
>> it
>>>>>> is on when booting, and blinks after booting finished).
>>>>>>
>>>>>> I don't have any former experience with u-boot. So please let me know
>>>>>> if there is any more info I should provide.
>>>>>>
>>>>>> Any help would be much appreciated! Thank you!
>>>>>>
>>>>>> --
>>>>>> Regards,
>>>>>> Chao Xu
>>>>>> _______________________________________________
>>>>>> U-Boot mailing list
>>>>>> U-Boot at lists.denx.de
>>>>>> http://lists.denx.de/mailman/listinfo/u-boot
>>>>>
>>>>>
>>>>
>>>>
>>>>
>>>> --
>>>> Regards,
>>>> Chao Xu
>>>
>>>
>>
>>
>>
>> --
>> Regards,
>> Chao Xu
>>
>
>
>
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