On 15.03.23 15:17, Michael Nazzareno Trimarchi wrote:
Hi
On Wed, Mar 15, 2023 at 3:13 PM Frieder Schrempf frieder.schrempf@kontron.de wrote:
Hi,
I'm trying to bring up a new board based on the i.MX8MP and I have an issue I'm hoping someone can help solving.
I'm seeing failures in the early SPL code, usually in the DDR initialization. Often they look like:
U-Boot SPL 2023.04-rc3 (Mar 07 2023 - 14:32:34 +0000) Training FAILED Failed to initialize DDR RAM! ### ERROR ### Please RESET the board ###
But sometimes ddr_init() doesn't even return an error and only the get_ram_size() afterwards which tries to allocate the memory fails.
In my experience you don't have space inside the cpu internal memory. It means that you overlap some stack with the code. Change the printf means move a bit. So you have problem but depends what you are going to destroy
Thanks for your reply. That's exactly what I'm thinking, too.
The strange thing is that the issues appear or disappear deterministically on the binary level. This means I sometimes get a U-Boot binary which runs just fine in 100% of cases. Then I change for example one of the following:
- Adding a single printf() somewhere in the boards spl.c
- Using the same binary but booting from SD card instead of USB loader
- Using the same source but switching from the OS cross compiler to the
one from Yocto/OE
And afterwards I get 100% failure rate with an error as described above.
My suspicion is that there is some memory corruption/conflict. My SPL is quite large and I wonder if it exceeds some limit.
SPL is loaded to 0x920000 and CONFIG_SPL_STACK is set to 0x960000, which leaves 256 KiB in between for the SPL. But all i.MX8MP boards seem to set CONFIG_SPL_MAX_SIZE=0x26000 (152 KiB) for some reason. My u-boot-spl-ddr.bin currently has around 193 KiB but I don't get any warning about exceeding the SPL_MAX_SIZE.
My questions:
- Why is CONFIG_SPL_MAX_SIZE set to 152 KiB?
I guess the remainder between the SPL code and the SPL stack is for the DDR firmware. Which explains why I get failures with SPL exceeding 152 KiB size.
Now I also understand the reason why the power init code was implemented using legacy non-DM drivers in other i.MX8MP boards. I probably also need to do this to save some space.
- Why is there no warning in my case?
Still, I fail to see why there isn't any error or where the size check is even implemented.
- Any other ideas or pointers?
Thanks for your help!
Best regards Frieder