[U-Boot] No console output once kernel starts loading.

[U-Boot] No console output once kernel starts loading.

[DaveKucharczyk]

I'm currently working on the kernel dtb for our MX53 board. 

U-boot loads the dtb and kernel and then gets stuck at "starting kernel...". 

I've triple checked the uart pad setup in imx53.dtsi

Here is my entire dts (everything else is stripped for testing)...
-----------------------------
/dts-v1/;
#include "imx53.dtsi"

/ {
   model = "Freescale i.MX53 test Board";
   compatible = "fsl,imx53-qsb", "fsl,imx53";

   memory {
      reg = <0x70000000 0x80000000>;
   };
&uart2 {
   pinctrl-names = "default";
   pinctrl-0 = <&pinctrl_uart2_3>;
   status = "okay";
};
&esdhc2 {
   pinctrl-names = "default";
   pinctrl-0 = <&pinctrl_esdhc2_1>;
   //cd-gpios = <&gpio4 1 0>;
   //wp-gpios = <&gpio2 9 0>;
   //lctl-gpios = <&gpio6 9 0>;
   status = "okay";
};
--------------------------------
Should I see console output with just the above dts?  Basically I just want
to see some life, so all I have setup is the uart. The sd card setup doesn't
even matter this early. 

What am I missing?



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[U-Boot] No console output once kernel starts loading.

[DaveKucharczyk]

To update anyone who comes across this issue...

Yes, a stripped version of the dts, like above, is all that is necessary to
see console output. You just have to setup your uart pads correctly in
imx53.dtsi.

My main issue was the uart setting in .config. 

I had earlyprintk turned on and the uart port number is one based. It
defaulted to port 1 while ours is port 2 (mxc1).
 
This zero based/one based inconsistency has bit me more than once. ;-)

Initially I thought it was a machine type mismatch, but that proved to be
wrong. 

As a matter of fact I stripped all machine type references from u-boot and
kernel and it works fine.

My question is: Is it ok to remove machine type when using a newer version
of u-boot and linux?

The dtb has a model description, but no other handshake to validate the
system between u-boot and linux.


 



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[U-Boot] No console output once kernel starts loading.

[Fabio Estevam]

On Wed, Mar 11, 2015 at 2:29 PM, DaveKucharczyk
<david.kucharczyk@gmail.com> wrote:

> My question is: Is it ok to remove machine type when using a newer version
> of u-boot and linux?

Yes, it is OK. With dt we no longer have to add the machine type numbers.

[U-Boot] No console output once kernel starts loading.

[Graeme Russ]

Hi David,


On 05/03/15 09:46, DaveKucharczyk wrote:
> I'm currently working on the kernel dtb for our MX53 board.
>
> U-boot loads the dtb and kernel and then gets stuck at "starting kernel...".
>
> I've triple checked the uart pad setup in imx53.dtsi

This is probably a long shot, but I had the same issue when I did the 
original x86 port. It turned out that I had not routed the UART 
interrupt signal correctly in U-Boot - I think the Linux kernel may have 
been waiting on some kind of interrupt from the UART (probably buffer 
empty) before it sent anything to it.

Regards,


Graeme