AM6442: DRIVER OFF mode

Kanae

Part Number: AM6442
Other Parts Discussed in Thread: AM5746

Tool/software:

Hi Support Team,

Customer who used AM5746 in the previous product has a question about AM6442 which is now being used.

Is it possible to realize the SIGNAL NAME's DRIVER OFF mode that was possible with the AM5746 with the AM6442's Pinmux as well?
The AM6442 PAD Configuration Register has bit 21 as TX_DIS, so I understand that it can be operated at the Register level,
but can you please tell me how to operate it with Pinmux?

Is there any way to do this without modifying the Devicetree file each time?

Best Regards,
Kanae

over 1 year ago

0 Andreas Dannenberg over 1 year ago

TI__Guru 70392 points

I'm out of the office on Monday, but will look into this after my return. Thanks.

0 Kanae over 1 year ago in reply to Andreas Dannenberg

Guru 10225 points

Hi Andreas,

Thank you for your support.
I look forward to your reply.

Best Regards,
Kanae

0 Andreas Dannenberg over 1 year ago in reply to Kanae

TI__Guru 70392 points

Hi Kanae-san,

what is the purpose of trying to set TX_DIS?

When you look at the K3 (AM6x) main Linux DTS include file for pin control, none of the modes that are used set the TX_DIS=1 bit, see https://git.ti.com/cgit/ti-linux-kernel/ti-linux-kernel/tree/arch/arm64/boot/dts/ti/k3-pinctrl.h?h=ti-linux-6.1.y

The way this actually works is our pinmux drivers always _clear_ TX_DIS (basically _enabling_ the output driver circuit) during pinmux initialization. However whether the output driver is ACTUALLY enabled or not is dependent on the configured MUX mode, and in some cases urther on the peripheral that gets muxed to the pin (e.g., GPIO). So you could say that TX_DIS=0 really is more about like "allow the output driver to be used if needed by the associated peripheral module" rather than a "hard enable". This being said the user does not need to configure this pin.

Here's some more background on this: https://e2e.ti.com/support/processors-group/processors/f/processors-forum/1283975/dra829j-padconfig-rxactive-and-tx_dis-meaning-and-purpose/4874107#4874107

Regards, Andreas

0 Kanae over 1 year ago in reply to Andreas Dannenberg

Guru 10225 points

Hi Andreas,

Thank you for your support.

The purpose of setting TX_DIS is to enable the DRIVER OFF mode,
which was available in the AM5746 that the customer used in previous development,
in the AM6442 Pinmux as well.
Since the 21st bit in the PAD Configuration Register is set to TX_DIS,
it can be operated at the register level, so the customer wanted to check
if it is possible to operate it with Pinmux.

I understood that AM64x does not provide Pinmux operation.
I will share your answer with our customers.

Best Regards,
Kanae

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AM6442: DRIVER OFF mode