AM62A7: GPIO_0 module reserved GPIOs

S. One

Part Number: AM62A7

Tool/software:

In the AM62ax reference manual, it says the following:

"Since MCU_GPIO0_[23:143], GPIO0_[87:143], and GPIO1_[88:143] are reserved in this device, general purpose interface supports up to 198 pins"

What are these pins reserved for? What are the implications of changing the 'ti,ngpio' Device Tree property for the module's node and using these pins. I see no other references to the reservation of these GPIOs and the purpose for doing so in the manual.

Thank you!

4 months ago

0 Anshu Madwesh 4 months ago

TI__Genius 13860 points

Hello,

Those pads don't have the pinmux option to support GPIOs. Refer to the AM62Ax Datasheet Section 6.3.10 GPIO & Table 6-1. Pin Attributes for the full list: https://www.ti.com/lit/ds/symlink/am62a7.pdf

GPIO0 supports 92 GPIOs and GPIO1 supports 52 which is reflected in the device tree: https://git.ti.com/cgit/ti-linux-kernel/ti-linux-kernel/tree/arch/arm64/boot/dts/ti/k3-am62a-main.dtsi?h=ti-linux-6.6.y#n541

And MCU_GPIO0 supports 24: https://git.ti.com/cgit/ti-linux-kernel/ti-linux-kernel/tree/arch/arm64/boot/dts/ti/k3-am62a-mcu.dtsi?h=ti-linux-6.6.y#n138

These reserved pads exist to support specific functions like oscillators, CSI, USB, debugger subsystem, and other general system uses. None of these pads are capable of being GPIOs hence they are 'reserved in the device'.

Best Regards,

Anshu

0 S. One 4 months ago in reply to Anshu Madwesh

Prodigy 20 points

Hi Anshu,

Thank you for your reply. That makes sense. However, I am still a little confused when the reference manual says that GPIO0[87:143] are reserved. Looking at the sections of the datasheet that you sent, GPIO0[87:91] seem have the option to be muxed as GPIO pins. This contradicts what the reference manual says. Is it possible that I have an outdated reference manual or something like that? I'd just like some clarification on this before marking as resolved :)

Thanks!

0 Anshu Madwesh 4 months ago in reply to S. One

TI__Genius 13860 points

Hello,

I agree, the GPIO pin ranges seems to conflict. From tracking on Git, looks like the change was made to align with the datasheet: https://git.ti.com/cgit/ti-linux-kernel/ti-linux-kernel/commit/arch/arm64/boot/dts/ti/k3-am62a-main.dtsi?h=ti-linux-6.6.y&id=92e2eaa44a7f368dfa6e66428fc42f3eefa6baa3

I'll check on this internally. If this is a documentation error, I'll file a bug to get this fixed in the next revision of the TRM.

Please ping this thread if you have not heard back by Tuesday next week.

Best Regards,

Anshu

0 S. One 4 months ago in reply to Anshu Madwesh

Prodigy 20 points

Great, thank you Anshu!

0 Anshu Madwesh 4 months ago in reply to S. One

TI__Genius 13860 points

Hello,

A bug has been filed to fix the documentation & will be added to the next revision of the TRM.

Thanks,

Anshu

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AM62A7: GPIO_0 module reserved GPIOs