DRA75: To disable emac or uart from linux kernel

Padmesh K Gopi

Part Number: DRA75

Hi,

I am trying to early boot on M4 core a customized EMAC example project or I2C project of ti-processor-sdk-rtos-automotive-dra7xx-evm-04.03.00.05, but am not able to visualize the required output as i believe that the kernel tries to use the peripheral access buses which affects the early boot functioning.

How do I disable ethernet or I2C or UART access of linux kernel ?

Regards,

Padmesh

over 6 years ago

0 Yordan Kamenov over 6 years ago

TI__Mastermind 42515 points

Hi Padmesh,

I am not sure that you need to disable those peripherals in the kernel. Can you check the u-boot patch mentioned here:
processors.wiki.ti.com/.../Early_Boot_and_Late_Attach_in_Linux

it will bring up some peripherals needed by M4 firmware (you many need more changes based on the peripherals used by your M4 application)

Can you try this and see if you have any progress?

Regards,
Yordan

0 Padmesh K Gopi over 6 years ago in reply to Yordan Kamenov

Expert 2610 points

Hi Yordan,

I have already applied those patches.
Referring to e2e.ti.com/.../2735826, it helps disable CAN. Similarly are there anything for these peripherals.

Regards,
Padmesh

0 Padmesh K Gopi over 6 years ago in reply to Padmesh K Gopi

Expert 2610 points

the link I referred to is
e2e.ti.com/.../2735826

0 Yordan Kamenov over 6 years ago in reply to Padmesh K Gopi

TI__Mastermind 42515 points

Hi Padmesh,

I will ping an expert to provide further help with early boot late attach.

Regards,
Yordan

0 Shravan Karthik over 6 years ago in reply to Padmesh K Gopi

TI__Genius 14650 points

Hi Padmesh,

I assume you're using Processor-SDK Vision? If yes, the Linux kernel branch for Processor-SDK Vision already had hooks in the DTB to disable devices from Linux (A15) which are used by RTOS cores (M4 / DSP / EVE). The source for the kernel can be found here: git.ti.com/.../vsdk-on-psdkla3.04

If you observe the file arch/arm/boot/dts/dra7-evm-infoadas.dts, you'll notice DISABLE_COMPLETE entries which prevent modules from being reset / idled from Linux (I2C-2 is completely disabled from Linux in this DTB).

You will also need this patch which prevents idling of modules from Linux (the below patch does it for I2C-2, please apply the same for modules you wish to disable from Linux).

git.ti.com/.../bd115bb22d650e02d3bcb69206fbd9bf5d349e0e

Regards
Shravan

0 Padmesh K Gopi over 6 years ago in reply to Shravan Karthik

Expert 2610 points

Hi Shravan,

We are not using Vision SDK instead we use processor sdk linux. We were not able to find the file dra7-evm-infoadas.dts.

Regards,
Padmesh

0 Shravan Karthik over 6 years ago in reply to Padmesh K Gopi

TI__Genius 14650 points

Hi Padmesh,

The source to the Linux tree where this is implemented was provided in the previous post. Please clone it and use the DTS mentioned as reference and modify the device tree you're using accordingly.
You will also need the patch provided in the previous link.

Regards
Shravan

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DRA75: To disable emac or uart from linux kernel