regulator in dts

[niklasmolin]

Hi.

I'm trying to get my custom board running the linux image.

I have based my image on the SabreSD, but I can't see that the Linux kernel is starting.

I'm wondering if I might have missed something in the dts/dtsi files.

I can also add that we are using an i.MX6D instead of Q (does this change anything how I configure the system?).

I can see that in the sabresd dtsi file they are using some regulators (I assume this is the external regulators on the sabreSD board).

I could se in the sabrelite that they used 3.3 and 2.5V regulators (out board is using a non CPU controlled power, like the sabrelite board).

Question 1, what does this regulator definition do?

Q 2. Do I need to set this if I'm using "pre"-fixed powers?

Q 3. I noticed that in the sabresd dtsi, it also sets up gpc, which the sabrelite doesn't.

Is this something I need to think about too?

Right now I can start u-boot, but when it comes to "Starting kernel ...." it hangs.

I can run the same image on the SabreSD board, and it has no problem to start the Linux kernel.

Do I need to do any modification because it's a i.MX6D instead of Q?

Thanks,

Niklas

[AnsonHuang]

Hi, Niklas

     See below the answer based on my understanding:

Question 1, what does this regulator definition do?

[Anson] regulator definition in dts is for regulator driver to initialize/config regulators when kernel boot up, I don't think it is the root cause, as the regulator driver is loader late after kernel start, you should be able to see some logs before that. Actually, even you remove all the regulators definition in dts, kernel should be able to boot up and show some logs.

Q 2. Do I need to set this if I'm using "pre"-fixed powers?

[Anson] if you suspect the regulators may cause this issue, you can try to enable all of them in uboot.

Q 3. I noticed that in the sabresd dtsi, it also sets up gpc, which the sabrelite doesn't.

Is this something I need to think about too?

[Anson] GPC node in dts is not impacting anything during kernel boot up.

Right now I can start u-boot, but when it comes to "Starting kernel ...." it hangs.

[Anson] Better to enable earlyprintk to see whether there is any log, or use JTAG to see whether did the kernel hang.

I can run the same image on the SabreSD board, and it has no problem to start the Linux kernel.

Do I need to do any modification because it's a i.MX6D instead of Q?

[Anson] Should be no any changes needed.

[fabio_estevam]

Can you show your full log including U-boot log?

It would be helpful if you post your dts patch so that we know what you have changed there.

Regards,

Fabio Estevam