[REGRESSION] Re: [PATCH v11 00/11] Add support for dynamic MMU configuration

[Anshul Dalal]

On Tue Oct 28, 2025 at 10:26 PM IST, Emanuele Ghidoli wrote:
> On 28/10/2025 05:38, Anshul Dalal wrote:
>> Hi Francesco,
>> 
>> On Mon Oct 27, 2025 at 10:22 PM IST, Francesco Dolcini wrote:
>>> Hello Anshul,
>>>
>>> On Fri, Oct 17, 2025 at 06:45:22PM +0530, Anshul Dalal wrote:
>>>> Hi all,
>>>>
>>>> In U-Boot, TI only provides a single memory map for all k3 platforms, this
>>>> does not scale for devices where atf and optee lie outside the range 0x80000000
>>>> - 0x80080000 and 0x9e780000 - 0xa0000000 respectively.
>>>>
>>>> There are also issues for devices with < 2GiB of memory (eg am62SiP with 512MiB
>>>> of RAM) as the maximum size for the first DRAM bank is hardcoded to 2GiB in the
>>>> current memory map. Furthermore the second DRAM bank is mapped even for devices
>>>> that only have a single bank.
>>>>
>>>> Therefore this patch set adds the required functionality to create the MMU table
>>>> at runtime based on the device-tree.
>>>>
>>>> The patch set has been build tested on all effected platforms but boot-tested
>>>> only on TI's K3 EVMs, the beagleplay and phytec's phycore-am6* platforms.
>>>>
>>>> The following effected boards have not been boot tested:
>>>>  - verdin-am62
>>>
>>> it seems that this series introduce a regression on verdin-am62, I have
>>> not done a bi-sect yet, but we run daily build of U-Boot master and the
>>> regressions seems to have started when this patch series was
>>> merged.
>>>
>>> On verdin-am62 we detect the RAM size at run-time, see
>>> board/toradex/verdin-am62/verdin-am62.c:dram_init(), and now we always
>>> get 2GiB even for modules with only 512MB or 1024MB of memory.
>>>
>> 
>> This patch series modified the behavior of enable_caches to configure the
>> memory map of the device as per the device-tree instead of using a
>> static map for all of K3.
>> 
>> The issue with verdin-am62 seems to be that while you do properly
>> configure gd->ram_size in your dram_init, the '/memory' node of the
>> device-tree remains unchanged with the outdated 2GiB size.
>> 
>> You could try updating the fdt's memory size to the correct value in
>> dram_init and see if that fixes the problem.
>> 
>> Regards,
>> Anshul
> Hello Anshul,
>
> I was bisecting the series, and I can confirm that the commit "mach-k3: map
> all banks using mem_map_from_dram_banks" introduces the regression.
>
> Given that initcall_run_f() calls dram_init_banksize(), and after relocation
> board_init_r() calls enable_caches() (call stack: board_init_r() ->
> initcall_run_r() -> initr_caches() -> enable_caches()), I would expect that
> enable_caches() should not override the bank sizes previously configured.
> Currently, however, enable_caches() introduces this side effect.
>
> Wouldn’t it make more sense to call fdtdec_setup_memory_banksize() in the
> default dram_init_banksize() (in arch/arm/mach-k3/k3-ddr.c) and avoid calling
> it again in mem_map_from_dram_banks()?
>

We could follow that order too but that would makes a call to
mem_map_from_dram_banks dependent on gd->bd->di_dram being correctly
populated. I had assumed whoever calls mem_map_from_dram_banks had made
sure to properly fixup the memory node of the fdt.

Given that it seems like the root cause of the problem is with the
U-Boot's device-tree not having the correct memory node, we could add a
call to fixup_memory_node (arch/arm/mach-k3/k3-ddr.c) from A53 SPL to
ensure the memory can be queried stright from the device-tree once we do
get to U-Boot proper.

	--- a/board/toradex/verdin-am62/verdin-am62.c
	+++ b/board/toradex/verdin-am62/verdin-am62.c
	@@ -46,6 +46,13 @@ int dram_init_banksize(void)
		return ret;
	 }

	+#ifdef CONFIG_XPL_BUILD
	+void spl_perform_board_fiups(struct spl_image_info *spl_image)
	+{
	+       fixup_memory_node(spl_image);
	+}
	+#endif
	+
	 /*
	  * Avoid relocated U-Boot clash with Linux reserved-memory on 512 MB SoM
	  */


If you could get to U-Boot prompt with the above diff, could you
share the output of the 'meminfo' command with the following configs
added:
	CONFIG_CMD_MEMINFO=y
	CONFIG_CMD_MEMINFO_MAP=y

Though so far, I have been unsuccessful in my attempts to reproduce a
boot failure on our own 512MiB platforms (AM62x SiP). Could you share
the boot logs with '#define DEBUG' in common/board_r.c, common/board_f.c
and mach-k3/common.c to help further narrow down the issue.

Regards,
Anshul