Re: [PATCH v6 06/11] arm64: dts: ti: k3-am62a7-sk: Enable IPC with remote processors

Andrew Davis
2025-04-10T18:22:40Z

On 4/10/25 6:38 AM, Devarsh Thakkar wrote:
> Hi Jai,
>
> On 10/04/25 15:48, Jai Luthra wrote:
>> Hi Devarsh,
>>
>> Thanks for the cc here.
>
> Thanks for the quick comments.
>
>>
> <snip>
>
>> On the basic camera + ISP usecase, afaiu the downstream edgeAI SDK uses
>> custom gstreamer elements that make calls to the aforementioned R5 core
>> that controls the ISP. On top of that there are additional gstreamer
>> patches that are not yet posted upstream for review from the community,
>> so the userspace design isn't really set in stone, or upstream-friendly
>> yet.
>>
>
> I don't see much relation of carve-outs with Gstreamer or it's pending downstream patches. The memory is mainly managed from firmwares (mainly openvx layer being used underneath) and there are even non-gstreamer pure openvx based use-cases/tests which use these carveouts. At the end of the day, the firmwares from the only SDK which is released publicly for AM62A uses all these carveouts.
>

These are programmable cores, you can run whatever you want on them. You can
make your own firmware if you like, we have support for them in our MCU+(FreeRTOS)
offering today[0](look at all these firmware you can build/run!).

In a week or so I'll start pushing support for these cores into Zephyr,
bringing in even more firmware options for these cores.

I simply do not see why one firmware, shipped with one of our SDKs*, doing
things wrong should force us to hack up our DT here in upstream Linux.

*Speaking of the "only" SDK's firmware, if you take our Yocto meta-ti layer and
build an SDK yourself, you get firmware by default that *doesn't need extra
carveouts*! [1][2]

Andrew

[0] https://github.com/TexasInstruments/mcupsdk-core-k3/blob/k3_main/makefile.am62ax
[1] https://git.yoctoproject.org/meta-ti/tree/meta-ti-bsp/recipes-bsp/ti-rtos-fw/ti-rtos-echo-test-fw.bb
[2] https://git.ti.com/cgit/processor-firmware/ti-linux-firmware/tree/ti-ipc/am62axx?h=ti-linux-firmware

>
>> IMO if that architecture is still under discussion, it might be better
>> to keep the edgeAI specific carveouts out of the upstream DTs.. just in
>> case the carevouts have to go away, or change significantly.
>>
>> If you are sure that the regions and firmware architecture is set in
>> stone and won't be updated even if there is a complete redesign of the
>> userspace/application level stack for accessing the ISP (let's say u
> sing> libcamera), only then it makes sense to add the carveouts right now.
>
>
> Yes as I said if whole firmware arch is getting updated then better to wait. I think probably the firmware team marked in cc can comment on that. Moreover I don't see any point of adding only half the regions as that would anyway not work with SDK supplied firmwares, for e.g. RTOS-to-RTOS ipc test run by firmwares on bootup would fail, along with other camera+ISP and AI use-cases.
>
> Regards
> Devarsh
>
>>>>>
>>>>> I understand your point, currently with this patch remoteproc loading
>>>>> will not work for some cores. However, the goal here is to standardize
>>>>> as much as possible the memory carveout sizes, push the "demo firmware"
>>>>> to request resources the correct way from resource table, and move away
>>>>> from this dependency and limitations that we have with our firmware.
>>>
>>> I understand this, but my view is that w.r.t firmware only goal should not
>>> just be tp demonstrate correct way of requesting resources from
>>> resource-tables, optimize the carve-outs etc but also to demonstrate the
>>> primary use-cases (camera+ISP+edgeAI) which the device is capable of.
>>>
>>>>> should soon be able to generate our own firmware using Zephyr,  which
>>>>> Andrew is pioneering, so with this firmware we should move to the
>>>>> correct direction upstream. Downstream we are still using the memory
>>>>> carveout sizes that the firmware folk want so desperately to keep, for
>>>>> now..
>>>>>
>>>>
>>>> +1
>>>>
>>>> I have this Zephyr based firmware for AM62A working and it uses the
>>>> standard IPC regions as specified in this patch. I'll be posting the PR
>>>> for it in Zephyr upstream by the end of week.
>>>>
>>>
>>> I understand this, but will this zephyr based firmware support vision +
>>> edgeAI analytics ? Does it demonstrate all the unique capabilities of AM62A
>>> SoC ? If not, then what would be utility of such firmware on AM62A where
>>> these are the primary use-cases w.r.t AM62A ?
>>>
>>> Why should upstream device-tree use carve-outs which match to this demo
>>> zephyr based firmware (which apparently not many are using and is not going
>>> into any official SDK release) instead of official firmwares going into SDK
>>> ? SDK released firmwares are being used by so many customers and SDK
>>> documentation maps to it, but zephyr firmware that is being pitched here,
>>> who would be the potential users and what would be it's utility ?
>>>
>>> [1]: https://www.ti.com/tool/PROCESSOR-SDK-J721E
>>>
>>> Regards
>>> Devarsh
>>>
>>>> For this patch as it is:
>>>>
>>>> Acked-by: Andrew Davis <afd@ti.com>
>>>>
>>>
>>>
>>>> Andrew
>>>>
>>>> [0] https://lore.kernel.org/lkml/20241011123922.23135-1-richard@nod.at/
>>>> [1] https://git.ti.com/cgit/edgeai/meta-edgeai/tree/recipes-kernel/
>>>> linux/linux-ti-staging/j721e-evm/0001-arm64-dts-ti-Add-DTB-overlays-for-
>>>> vision-apps-and-ed.patch?h=kirkstone
>>>>
>>>>> ~ Judith
>>>>>
>>>>>>
>>>>>> [1]:
>>>>>> https://git.ti.com/cgit/ti-linux-kernel/ti-linux-kernel/tree/
>>>>>> arch/arm64/boot/dts/ti/k3-am62a7-sk.dts?h=ti-linux-6.6.y-cicd#n103
>>>>>> [2]: https://www.ti.com/tool/PROCESSOR-SDK-AM62A
>>>>>>
>>>>>> Regards
>>>>>> Devarsh
>>>>>>
>>>>>>>        opp-table {
>>>>>>> @@ -741,3 +771,57 @@ dpi1_out: endpoint {
>>>>>>>            };
>>>>>>>        };
>>>>>>>    };
>>>>>>> +
>>>>>>> +&mailbox0_cluster0 {
>>>>>>> +    status = "okay";
>>>>>>> +
>>>>>>> +    mbox_r5_0: mbox-r5-0 {
>>>>>>> +        ti,mbox-rx = <0 0 0>;
>>>>>>> +        ti,mbox-tx = <1 0 0>;
>>>>>>> +    };
>>>>>>> +};
>>>>>>> +
>>>>>>> +&mailbox0_cluster1 {
>>>>>>> +    status = "okay";
>>>>>>> +
>>>>>>> +    mbox_c7x_0: mbox-c7x-0 {
>>>>>>> +        ti,mbox-rx = <0 0 0>;
>>>>>>> +        ti,mbox-tx = <1 0 0>;
>>>>>>> +    };
>>>>>>> +};
>>>>>>> +
>>>>>>> +&mailbox0_cluster2 {
>>>>>>> +    status = "okay";
>>>>>>> +
>>>>>>> +    mbox_mcu_r5_0: mbox-mcu-r5-0 {
>>>>>>> +        ti,mbox-rx = <0 0 0>;
>>>>>>> +        ti,mbox-tx = <1 0 0>;
>>>>>>> +    };
>>>>>>> +};
>>>>>>> +
>>>>>>> +&wkup_r5fss0 {
>>>>>>> +    status = "okay";
>>>>>>> +};
>>>>>>> +
>>>>>>> +&wkup_r5fss0_core0 {
>>>>>>> +    mboxes = <&mailbox0_cluster0>, <&mbox_r5_0>;
>>>>>>> +    memory-region = <&wkup_r5fss0_core0_dma_memory_region>,
>>>>>>> +            <&wkup_r5fss0_core0_memory_region>;
>>>>>>> +};
>>>>>>> +
>>>>>>> +&mcu_r5fss0 {
>>>>>>> +    status = "okay";
>>>>>>> +};
>>>>>>> +
>>>>>>> +&mcu_r5fss0_core0 {
>>>>>>> +    mboxes = <&mailbox0_cluster2>, <&mbox_mcu_r5_0>;
>>>>>>> +    memory-region = <&mcu_r5fss0_core0_dma_memory_region>,
>>>>>>> +            <&mcu_r5fss0_core0_memory_region>;
>>>>>>> +};
>>>>>>> +
>>>>>>> +&c7x_0 {
>>>>>>> +    mboxes = <&mailbox0_cluster1>, <&mbox_c7x_0>;
>>>>>>> +    memory-region = <&c7x_0_dma_memory_region>,
>>>>>>> +            <&c7x_0_memory_region>;
>>>>>>> +    status = "okay";
>>>>>>> +};
>>>>>>
>>>>>
>>>>
>>>
>>>
>>
>