[PATCH v2] configs: am571x_hs_evm_defconfig: Reserve EMIF memory used by PPA

[Andrew Davis]

On 12/5/25 1:32 AM, Beleswar Prasad Padhi wrote:
> 
> On 02/12/25 18:47, Andrew Davis wrote:
>> On 12/1/25 11:56 PM, Beleswar Prasad Padhi wrote:
>>>
>>> On 02/12/25 00:58, Andrew Davis wrote:
>>>> On 11/28/25 9:04 AM, Beleswar Padhi wrote:
>>>>> The AM571x SoC has 1 GB DDR space. As part of normal re-location process
>>>>> U-Boot copies itself to the top of DDR bank. However, on HS devices, the
>>>>> top 37 MB is used by PPA and is firewalled. This results in an exception
>>>>> and the boot fails.
>>>>>
>>>>> Introduce a new defconfig for AM571x HS platforms and set
>>>>> CONFIG_SYS_MEM_TOP_HIDE to reserve the top 38 MB memory (aligned to 2MB
>>>>> as per page size for ARM32) for the same.
>>>>>
>>>>
>>>> This "SYS_MEM_TOP_HIDE" looks new, for other OMAP-class HS devices we
>>>> use "CFG_PRAM"[0], seems these two configs do the same thing, could probably
>>>> combine them in some way..
>>>>
>>>> As CFG_PRAM is set based on TI_SECURE_EMIF_TOTAL_REGION_SIZE which is 32MB
>>>
>>>
>>> CFG_PRAM is only set if TI_SECURE_EMIF_REGION_START is not set, but we
>>> have it set it to 0xbdb00000 in the am57xx_hs_evm_defconfig.
>>>
>>> https://github.com/u-boot/u-boot/blob/master/include/configs/ti_omap5_common.h#L75-L81
>>>
>>>> for all other AM57x, why is this needed only for AM571?
>>>
>>>
>>> Other AM57x boards have >1 GiB DDR. So, the top of DDR space does not
>>> intersect with the firewalled EMIF region (0xbdb00000). Only in case of
>>> AM571x, the top of DDR collides with firewalled region, so boot fails while
>>> doing reloc.
>>>
>>
>> Is there some way to detect this at runtime? Nothing prevents any of the
>> AM57x SoCs being used on boards with 1GB DDR (although they also might use
>> a different defconfig). How do we deal with this for K3 devices? Some use
>> an OP-TEE address aligned at 512MB and I'm sure one of them have that amount
>> of DDR.
> 
> 
> Well, actually not...
> It's the AM62 SIP platform. From DT, it would look like OPTEE is at the top of the
> DDR[1], but we do a FDT fixup here in u-boot to replace the OPTEE to the start
> of DDR[2]
> 
> [1]: https://github.com/torvalds/linux/blob/master/arch/arm64/boot/dts/ti/k3-am62x-sk-common.dtsi#L71
> [2]: https://github.com/u-boot/u-boot/blob/master/arch/arm/mach-k3/am62x/am625_fdt.c#L84
> 
> I am not sure if we can do such a thing here for mem used by PPA/firmware
> as it could assume it has that memory hardcoded.
> 
>>
>>>> We build for all
>>>> the AM57x with one defconfig, so this new defconfig will go unused. Just set
>>>> the default CFG_PRAM size to 64MB (same as AM43x),
>>>
>>>
>>> I am guessing all AM43x devices have the same amount of memory unlike
>>> AM57x devices? If we set CFG_PRAM to 38MB by default, won't we lose out
>>> that memory on other devices which do not face this limitation?
>>>
>>
>> We only really supported "officially" the AM437x-EVM. But our over-focus
>> on just our EVMs caused us to make assumptions that would later make
>> it difficult to add support for customer boards. Assuming DDR size was
>> one such assumption, and should a customer board have the "wrong" DDR
>> size things like this would break.
>>
>> So instead of making another one-off fix to get one of our EVMs working,
>> I'm trying to think of a way we can make this work automatically for any
>> combination of DDR size and firewalled region.
> 
> TL;DR
> I think adding that dynamic support would be tied up only for TI usecase?
> 
> Hmm yes, I get your point. But to be able to do this dynamically, we
> would want to see if gd->relocaddr intersects with CFG_PRAM:
> 
> Case 1:
> gd->relocaddr > (SECURE_REGION_START + SECURE_REGION_SIZE)
> = Best case. U-Boot relocates to an address higher than firewalled addr
> 
> Case 2:
> gd->relocaddr <= (SECURE_REGION_START + SECURE_REGION_SIZE)
> = Fixup needed. U-Boot relocates to an address which could overlap
> with secure region. Update the gd->relocaddr to a lower address range
> which won't overlap with secure region:
> 
>      reloc_text_size = (RAM_TOP - gd->relocaddr);
>      gd->relocaddr = SECURE_REGION_START - reloc_text_size;
> 
> 
> And ofcourse, we can't put this logic in the existing 'reserve_pram'[3]
> INITCALL because gd->relocaddr gets modified in the subsequent
> initcalls like 'reserve_trace'. We would want to introduce a new
> INITCALL which would be invoked after all reserve_* initcalls and
> before the reloc_* initcalls; where we can put this logic.
> 
> Let me know if you think this is worth adding, or is an overkill and
> we can live happily with CFG_PRAM = 38 MB for all AM57x devices :)

Thanks for doing all this evaluation. I don't think this will be
the last time we run into this issue, but for now let's just make
CFG_PRAM = 64 MB for all AM57x devices and create the perfect solution
later.

Andrew

> 
> [3]: https://github.com/u-boot/u-boot/blob/master/common/board_f.c#L990
> 
> Thanks,
> Beleswar
> 
>>
>> Andrew
>>
>>> Thanks,
>>> Beleswar
>>>
>>>> should be enough for all
>>>> and doesn't hurt to have more than needed reserved to be safe.
>>>>
>>>> Andrew
>>>>
>>>> [0] https://github.com/u-boot/u-boot/blob/master/include/configs/am43xx_evm.h#L153
>>>>
>>>>> Signed-off-by: Beleswar Padhi <b-padhi at ti.com>
>>>>> ---
>>>>> Fix boot for TI AM571x HS EVM board
>>>>> v2: Changelog:
>>>>> 1. Drop [PATCH v1 2/2] in v2 series. There is no need to add reserved
>>>>> memory node in DT as it is done by U-Boot as part of FDT fixups
>>>>> https://github.com/u-boot/u-boot/blob/master/arch/arm/mach-omap2/fdt-common.c#L72-L107
>>>>> 2. Add entry in MAINTAINERS for new config.
>>>>> 3. Update commit message to use memory size in MB than raw hex bytes
>>>>>
>>>>> Link to v1:
>>>>> https://lore.kernel.org/all/20251128064353.1295063-1-b-padhi@ti.com/
>>>>>
>>>>> Test logs:
>>>>> https://gist.github.com/3V3RYONE/e86b3f4551986b0400d0e0f66d6ecc66
>>>>>
>>>>>     MAINTAINERS                     | 1 +
>>>>>     configs/am571x_hs_evm_defconfig | 3 +++
>>>>>     2 files changed, 4 insertions(+)
>>>>>     create mode 100644 configs/am571x_hs_evm_defconfig
>>>>>
>>>>> diff --git a/MAINTAINERS b/MAINTAINERS
>>>>> index b43dae882b3..e5d564cd760 100644
>>>>> --- a/MAINTAINERS
>>>>> +++ b/MAINTAINERS
>>>>> @@ -1780,6 +1780,7 @@ F:    configs/am335x_hs_evm_spi_defconfig
>>>>>     F:    configs/am335x_hs_evm_uart_defconfig
>>>>>     F:    configs/am43xx_hs_evm_defconfig
>>>>>     F:    configs/am43xx_hs_evm_qspi_defconfig
>>>>> +F:    configs/am571x_hs_evm_defconfig
>>>>>     F:    configs/am57xx_hs_evm_defconfig
>>>>>     F:    configs/am57xx_hs_evm_usb_defconfig
>>>>>     F:    configs/dra7xx_hs_evm_defconfig
>>>>> diff --git a/configs/am571x_hs_evm_defconfig b/configs/am571x_hs_evm_defconfig
>>>>> new file mode 100644
>>>>> index 00000000000..7e44ee5221a
>>>>> --- /dev/null
>>>>> +++ b/configs/am571x_hs_evm_defconfig
>>>>> @@ -0,0 +1,3 @@
>>>>> +#include <configs/am57xx_hs_evm_defconfig>
>>>>> +
>>>>> +CONFIG_SYS_MEM_TOP_HIDE=0x2600000
>>>>
>>