Re: Linux hangs on Tegra 2 / U-Boot board

[Stephen Warren <swarren-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org>]

On 07/24/2012 08:05 AM, Thierry Reding wrote:
> On Tue, Jul 24, 2012 at 01:32:59PM +0000, Nuno Santos wrote:
>> Hi
>> 
>> As I explained in a previous post, I have a Tegra2 based board
>> (Harmony) and (thanks to your help) I successfully managed to
>> flash and boot U-Boot.
>> 
>> However, I’ve been trying to boot Linux from U-Boot but to no
>> avail. Once the device runs U-boot, I load a Linux image into
>> memory over TFTP, run the command “bootm”, and then Linux
>> immediately hangs after printing message “Starting kernel ...".
>> 
>> I’ve tried multiple suggestions I’ve seen online: defining linux
>> console boot in the “bootargs” parameter in case it is a console
>> misconfiguration, recompile the kernel with CONFIG_DEBUG_LL to
>> diagnose the problem, and check the machine id (by providing
>> machine id 0xAAB in the environment var “machid”). In all these
>> attempts there is no change whatsoever in the output.
> 
> You need to pass earlyprintk in bootargs to see early debug output 
> (CONFIG_DEBUG_LL). Also make sure that you've flashed with the
> correct ODMDATA set so the output goes to the correct UART.

Also, you need an appropriate Kconfig option to select which debug
UART to use. CONFIG_TEGRA_DEBUG_UART_AUTO_ODMDATA should hopefully
work fine, assuming your ODMDATA contains the correct UART setting
(e.g. 0x300d8011 should work).

>> I’d be really grateful if someone could give me a hand on this.
>> So, here’s the details.
>> 
>> 1. I’m using the kernel from
>> git://nv-tegra.nvidia.com/linux-2.6.git, pulled today and
>> configured as indicated in the doc (make tegra_defconfig); the
>> compilation also creates a uImage for U-Boot. I’m using the
>> latest version of U-Boot, compiled locally using the standard
>> procedure.
> 
> It might help to try and run the upstream kernel just to check
> that everything works. I believe the NVIDIA downstream kernels
> currently don't boot properly when run from the upstream U-Boot.
> But I may be mistaken.

Upstream U-Boot has primarily (perhaps even only) been tested with an
upstream Linux kernel. Equally, our downstream kernels have mostly
only been tested with downstream fastboot, and partially with
downstream U-Boot. The upshot of this is that downstream kernels
incorrectly assume that the bootloader initializes a lot more stuff
(e.g. clocks). You will likely have much more luck booting an upstream
kernel, at least initially in order to get the process working.