SK-TDA4VM: Requests for Additional Documentation

Hi Jeffrey,

Thank you for your questions! To set some expectations, I will need about a week to gather information from the team since we are touching a lot of different components in this thread.

5. Maybe this answers some questions: https://e2e.ti.com/support/processors-group/processors/f/processors-forum/1008069/faq-tda4vm-enable-mcu_r5f-lockstep-using-spl-and-sbl 

Apologies for the inconvenience, and thank you for your patience.

Regards,

Takuma

Hi Jeffrey,

Found a thread related to question 7.

7. It seems like cpufreq is not supported: https://e2e.ti.com/support/processors-group/processors/f/processors-forum/1105091/tda4vm-did-and-how-to-support-cpufreq-governor?tisearch=e2e-sitesearch&keymatch=cpufreq#

Regards,

Takuma

Jeffrey Zampieron said:

7. Documentation on how to use and evaluate cpufreq scaling, if supported, on the A72 cores.

Hi,

DFS of Dynamic frequency scaling can be done from user space. TDA4VM does not support dynamic voltage frequency scaling. That said it does support
dynamic frequency scaling at the same voltage.

A detailed App note here: https://www.ti.com/lit/pdf/spracz5?keyMatch=DRA821

SDK does not support DFS. The app note mentioned above enables scaling CPU frequency from Linux user space using the k3conf tool.

Jeffrey Zampieron said:

3. Any documentation at all on power optimizing/power management the part for Idle in Linux. It's nice that TISCI documents C api calls in a library, but how is that integrated into the ti-sci driver that shows up in SysFS.

Right now I measure the EVM drawing 10W - 11W when doing nothing and just sitting at a prompt and about 15W when running the inference demos

There is support for MCU Only mode: https://e2e.ti.com/support/processors-group/processors/f/processors-forum/979733/tda4vm-tda4vm---mcu-only-mode/3628352#3628352

No support for suspend to RAM or any other low power modes.

Jeffrey Zampieron said:

. For Linux Drivers details about the SysFS interface and associated controls and supported features for those drivers. For example, does the Linux PCIe driver support power states? Does the SPI driver support suspend?

I've noticed that on the SK-TDA4VM the standard `echo "mem" > /sys/power/state` does not actually suspend due to failures to suspend various drivers

As mentioned above there is NO support for suspend to RAM on TDA4.

- Keerthy

w.r.t. using MCU-only mode... that article specifically refers to the J721E EVM, not the SK-TDA4VM.

I can check if the PMIC and PMIC wiring is the same, but I'm wondering if anyone else has attempted MCU only on this EVM.

Hi Jeffrey,

Jeffrey Zampieron said:

I'm wondering if anyone else has attempted MCU only on this EVM.

Most demos in MCUSW has not been validated on SK-TDA4VM, including MCU only mode, as the SK-TDA4VM and compatible SDK has a focus more on Linux running on A72 cores. Since EVM and SK boards are both using the same chip, theoretically many demos should still work, but since they are different boards we do not guarantee and support the full set of demos on the SK board. For MCU development, although the board is expensive, the recommendation is to buy the EVM.

Jeffrey Zampieron said:

1. For Linux Drivers details about the SysFS interface and associated controls and supported features for those drivers. For example, does the Linux PCIe driver support power states? Does the SPI driver support suspend?

The PCIe driver does not support ASPM, though the SOC has the support in hardware. This will need to further implemented by customer.

On SPI (OSPI) interface, there may be commands to put the NOR flash device to low power states, but it is not possible to power manage OSPI controller dynamically. i.e., user can turn the module ON and Off once, but not back on without a reset.

Jeffrey Zampieron said:

2. Details for each of the PDK drivers, which are used on Linux, on how they are wrapped into linux and accessed from user-space for the main cores.

Linux has it’s own drivers and will not use the PDK. PDK drivers are intended for baremetal or FreeRTOS based applications running on R5Fs, C6x & C7x. 

Jeffrey Zampieron said:

4. Details on the formats of the images for the secondary processors (R5's, DSPs, etc). There are some notes https://software-dl.ti.com/jacinto7/esd/processor-sdk-linux-jacinto7/08_02_00_03/exports/docs/linux/Foundational_Components/U-Boot/UG-General-Info.html#device-trees but the "following table" about the R5 cores is missing.

The image formats which will be consumed by the bootloader for the secondary processors R5Fs, DSPs will be stripped ELF images (xer5f, xe66, xe71). ELF image is a standard image format.

I will need some more time on 3 and 6.

Regards,

Takuma