[U-Boot] Is CCSRBAR relocation broken on P2020?

[Ira W. Snyder]

On Thu, Nov 10, 2011 at 11:12:41AM -0600, Timur Tabi wrote:
> Ira W. Snyder wrote:
> > Hello Timur, Kumar, U-Boot List,
> > 
> > I'm working on porting U-Boot to the Freescale P2020 COM-Express board.
> > See the ML post from 2011-09-27 titled "[PATCH 0/2] mpc85xx: support for
> > Freescale COM Express P2020".
> 
> I see that you are using a NAND boot, which is a multi-stage boot.  There are some problems with that that have been fixed in recent patches posted by me and Kumar to the U-boot mailing list.
> 
> In particular, one patches puts U-boot into an infinite loop if CCSR is relocated in the wrong step.
> 

I don't use NAND, nor any multi-stage boot (as far as I know).

I boot off of SDCARD (P2020COME_SDCARD_config). To write the U-Boot
image to the microSD card, I use a tool provided with the BSP called
"boot_format-1.0.0". Maybe you are familiar with it?

> > When it was posted, the port was working on the top of tree U-Boot. This
> > included relocation of the CCSRBAR from the power on location of
> > 0xff700000 to 0xffe00000.
> 
> Is there a reason why you want to relocate CCSR at all?  Everything would be a lot easier if you just left it at the default location.  I have a suspicion that many boards relocate CCSR just for the heck of it.
> 
> However, Kumar's recent rework of the device trees may force all P2020 boards to have the same CCSR, so you might be stuck.
> 

I relocate the CCSR because my device tree requires it. I wanted to use
the Linux arch/powerpc/boot/dts/p2020si.dtsi as a base, and override the
few things that are specific to this board. It requires the CCSR be
relocated to 0xffe00000.

I'll look at Kumar's DTS changes. I saw them on the Linux PPC ML.

> > Today I updated U-Boot to top of tree to address the comments in the
> > initial mailing list posting. Upon attempting to boot the board, I get
> > no console output. I have traced this to commit 6ca88b0958
> > ("powerpc/85xx: relocate CCSR before creating the initial RAM area").
> 
> This patch requires that only the last stage of U-Boot (i.e. the "real" U-Boot) relocate CCSR.  All previous stages must not relocate CCSR.  This is a change from the way we were doing things in the past.
> 

I understand that. I only use one U-Boot. To the best of my knowledge,
boot on this platform works like this:

- power on
- the P2020 looks for the magic "BOOT" written by the boot_format tool
  on the SD card
- the P2020 executes the instructions written by boot_format to setup
  RAM correctly, load the U-Boot from the SD card to RAM, and then jumps
  to it
- U-Boot runs, including relocating CCSR

Only one U-Boot is ever executed.

> > Indeed, making sure that the code does not run by adding the following
> > to my board config file causes U-Boot to start correctly. Though the
> > CCSRBAR is not relocated, as expected.
> > 
> > #define CONFIG_SYS_CCSR_DO_NOT_RELOCATE
> 
> If you set this macro and your DTS puts CCSR at 0xffe00000, then you won't be able to boot Linux (or any OS that uses the device tree).
> 

Of course. I have to get U-Boot working before I can boot any OS. This
was a way to test that the new code causes U-Boot to fail, nothing more.

It proved that there is something wrong with relocation on my board.

> > As an alternative, reverting the commit causes my board to work again.
> > The CCSRBAR is relocated correctly.
> 
> The new CCSR relocation method is needed to standardize the way we handle that task and to support future SOCs that require CCSR to be relocated earlier in the boot process.  I admit that it can sneak up on people, like it did for you, but the new approach is necessary.  In the end, it will make everything a lot easier.
> 

I understand that. Has the current top of tree been tested on P2020DS?
I'm looking for some assurance that the code I'm trying to use actually
works on a !CONFIG_FSL_CORENET platform which relocates the CCSR. One
in-tree example is the P2020DS.

> > The P2020DS board is very similar to the board I am using. It performs
> > the same relocation of the CCSRBAR that I want to use as well.  Does
> > anyone have a P2020DS that they can test with the current top of tree
> > U-Boot? Does it boot? Can you send the output of "md ffe00000 1"?
> 
> Kumar recently posted a patch that fixes the relocation on multi-stage U-Boots (e.g. NAND booting, SPI booting, etc).  I also posted a patchset last week that fixes a few problems with 
> 

Can you tell me the subject lines of these patches? Even though I don't
use a multi-stage U-Boot, I'll check them out.

Thanks for the reply,
Ira