BBB: queries on some pins fail

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1

Hello,

Request for status of some pins fails (whereas on others works):

debian@beaglebone:~$ config-pin -q p9.25
P9_25 pinmux file not found!
Cannot read pinmux file: /sys/devices/platform/ocp/ocpP9_25_pinmux/state
debian@beaglebone:~$ sudo config-pin -q p9.31
P9_31 pinmux file not found!
Cannot read pinmux file: /sys/devices/platform/ocp/ocpP9_31_pinmux/state

debian@beaglebone:~$ config-pin -q p9.24
P9_24 Mode: default Direction: in Value: 1
debian@beaglebone:~$

Why ?

Sincerely,

Pavel

2

Hello,

Request for status of some pins fails (whereas on others works):

debian@beaglebone:~$ config-pin -q p9.25
P9_25 pinmux file not found!
Cannot read pinmux file: /sys/devices/platform/ocp/ocp*P9_25_pinmux/state
debian@beaglebone:~$ sudo config-pin -q p9.31
P9_31 pinmux file not found!
Cannot read pinmux file: /sys/devices/platform/ocp/ocp*P9_31_pinmux/state

P9_25 and P9_31 default to hdmi audio, disable that overlay in
/boot/uEnv.txt and then config-pin will have generic access..

Regards,

3

Thanks !
The defaults are specified probably in one of .dts (or .dtsi) files. Which one ?
Regards.

4

It's lots of overlays: adc, hdmi, hdmi-audio, emmc, wireless, etc..

https://elinux.org/Beagleboard:BeagleBoneBlack_Debian#U-Boot_Disable_on-board_devices

Regards,

5

Well, but where this default specified ?
I mean on Power On how BBB “knows” that P.9.31 is reserved for audio ?
This default meaning is specified somewhere in device tree, isn’t it ?
Regards.

6

For the BBB, the default image has eMMC, HDMI with Audio, and ADC enabled..

debian@bbb-pwr01-ser09:~$ sudo /opt/scripts/tools/version.sh | grep UBOOT
UBOOT: Booted Device-Tree:[am335x-boneblack-uboot-univ.dts]
UBOOT: Loaded Overlay:[AM335X-PRU-RPROC-4-14-TI-00A0]
UBOOT: Loaded Overlay:[BB-ADC-00A0]
UBOOT: Loaded Overlay:[BB-BONE-eMMC1-01-00A0]
UBOOT: Loaded Overlay:[BB-HDMI-TDA998x-00A0]

The main *.dts file loaded (but compiled) is:

am335x-boneblack-uboot-univ.dts

With 4 overlays:
AM335X-PRU-RPROC-4-14-TI-00A0.dtbo -> provides pru
BB-ADC-00A0.dtbo -> provides ADC
BB-BONE-eMMC1-01-00A0.dtbo -> provides eMMC
BB-HDMI-TDA998x-00A0.dtbo -> provinces HDMI with Audio..

With the out - of box image, use this to disable those overlays:

https://elinux.org/Beagleboard:BeagleBoneBlack_Debian#U-Boot_Disable_on-board_devices

On the mainline kernel, am335x-boneblack.dts has all these enabled by default.

We allow users to disable them to grab the pins for other features.

Regards,

7

Request for status of some pins fails (whereas on others works):

  Suggest you install GitHub - mvduin/bbb-pin-utils: Pin utilities for BeagleBone Black

debian@beaglebone:~$ config-pin -q *p9.25*
P9_25 pinmux file not found!
Cannot read pinmux file: /sys/devices/platform/ocp/ocp*P9_25_pinmux/state

P9.25 / audio osc 107 fast rx up 0 asp 0 tx hclk
mcasp@48038000 (mcasp0_pins)

debian@beaglebone:~$ sudo config-pin -q *p9.31*
P9_31 pinmux file not found!
Cannot read pinmux file: /sys/devices/platform/ocp/ocp*P9_31_pinmux/state

P9.31 / hdmi audio clk 100 fast down 0 asp 0 tx clk
mcasp@48038000 (mcasp0_pins)

debian@beaglebone:~$ config-pin -q *p9.24*
P9_24 Mode: default Direction: in Value: 1

P9.24 97 fast rx up 7 gpio 0.15 << hi P9_24
(pinmux_P9_24_default_pin)

  You would have to disable the mcasp unit and maybe HDMI to free the
affected pins from dedicated usage and allow them to be exported -- this is
likely a device tree operation. Start with editing /boot/uEnv.txt