Linux/AM3359: unable to mux 3 pins as gpios

Scott Tower

Part Number: AM3359

Tool/software: Linux

Hello TI,

We have a custom board mostly based on the Beaglebone Black. I have been struggling mightily to mux 3 pins as gpios (simple right?) and I am unable to make that happen. The un-muxable pins are:

gpio0_1 (pin 83 (44e1094c.0)) ,
gpio2_21 (pin 80 (44e10940.0)), and
gpio3_18 (pin 104 (44e109a0.0)).

I am sure (famous last words) that my device tree is properly programmed, and I can include the fdtdump that shows that the pins reassigned as gpios if you want. But when I look at '/sys/kernel/debug/pinctrl/44e10800.pinmux.pins', it says

gpio0_1 never changed out of mode 0,
gpio2_21 never changed out of mode 0, and
gpio3_18 never changed out of mode 4.

Any advice *greatly* appreciated. Thank you.

Scott

over 7 years ago

0 Scott Tower over 7 years ago

Prodigy 160 points

to help with your investigations, the default pin assignments relate to the following hardware:
gpio0_1: mode 0 = MDIO_CLK
gpio2_21: mode 0 = GMII1_RXD0 , and
gpio3_18: mode 4 = MMC0_SDWP.

0 Scott Tower over 7 years ago in reply to Scott Tower

Prodigy 160 points

The pins that I cannot seem to change are being set in u-boot. I still do not understand why my device tree did not change the pins, but I ended up fixing the issue by modifying the u-boot source. Not a good answer, but it works.

0 Pavel Botev over 7 years ago in reply to Scott Tower

TI__Guru**** 170625 points

Hi Scott,

Have you check if any firmware is overwriting your pinmux settings?

Regards,
Pavel

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Linux/AM3359: unable to mux 3 pins as gpios