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

[Beleswar Prasad Padhi]

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 :)

[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
>>>
>