brgl
Trouble accessing pin infos on Dragonboard 410C
On the Dragonboard 410C, the function gpiod_chip_get_line_info can't access any of the pins of /dev/gpiochip0.
It can open the chip (gpiod_chip_open) and get the info (gpiod_chip_get_info). Hardware works fine. Code is ran as sudo.
Tried with 0 to 121, 390 to 511; same result.
Linux linaro 5.9.0-qcomlt-arm64 #138 SMP PREEMPT Sat Nov 21 00:47:13 UTC 2020 aarch64 GNU/Linux
PRETTY_NAME="Debian GNU/Linux forky/sid" NAME="Debian GNU/Linux" VERSION_CODENAME=forky ID=debian HOME_URL="https://www.debian.org/" SUPPORT_URL="https://www.debian.org/support" BUG_REPORT_URL="https://bugs.debian.org/"
libgpiod API version 2.2.1
I need more info, strace logs, the exact code you're running, what the error is etc.
I use 'linaro' for user name. I added a group 'gpiod' in /etc/group and added user 'linaro' to it. In fact there was many changes to the GPIO systems, but none worked with my setup no matter how the GPIO pin was specified, it always was inaccessible.
The hardware was brand new and no mishaps happened. I believe the hardware is all right.
The code is a modification of the example provided with the source of libgpiod. get_line_info.c.gz
My code just does very basic API calls and display the error in case of failure. I believe I made the API calls in a correct sequence by looking at the examples.
Here's the messages displayed when running: run-example.txt
Here is the trace: strace.log.gz
I used this board to use with the 'Internet of Things' courses at Coursera a few years ago. It was a show stopper for me. I hope the problems will be solved soon.
Thank you very much!
So I'm running the same board and getting this:
[ 0.000000] Booting Linux on physical CPU 0x0000000000 [0x410fd030]
[ 0.000000] Linux version 6.17.0-rc3-next-20250825 (brgl@brgl-build) (aarch64-linux-gnu-gcc (Ubuntu 14.2.0-19ubuntu2) 14.2.0, GNU ld (GNU Binutils for Ubuntu) 2.44) #105 SMP PREEMPT Mon Aug 25 18:36:07 CEST 2025
[ 0.000000] KASLR disabled due to lack of seed
[ 0.000000] Machine model: Qualcomm Technologies, Inc. APQ 8016 SBC
[snip]
root@qcom-armv8a:~# gpiodetect
gpiochip0 [1000000.pinctrl] (122 lines)
gpiochip1 [200f000.spmi:pmic@0:mpps@a000] (4 lines)
gpiochip2 [200f000.spmi:pmic@0:gpio@c000] (4 lines)
root@qcom-armv8a:~# gpioinfo -c gpiochip0
gpiochip0 - 122 lines:
line 0: "[UART0_TX]" input
line 1: "[UART0_RX]" input
line 2: "[UART0_CTS_N]" input
line 3: "[UART0_RTS_N]" input
line 4: "[UART1_TX]" output
line 5: "[UART1_RX]" output
line 6: "[I2C0_SDA]" input
line 7: "[I2C0_SCL]" input
line 8: "[SPI1_DOUT]" input
line 9: "[SPI1_DIN]" input
line 10: "[SPI1_CS]" input
line 11: "[SPI1_SCLK]" input
line 12: "GPIO-B" input
line 13: "GPIO-C" input
line 14: "[I2C3_SDA]" input
line 15: "[I2C3_SCL]" input
line 16: "[SPI0_MOSI]" input
line 17: "[SPI0_MISO]" input
line 18: "[SPI0_CS_N]" input
line 19: "[SPI0_CLK]" input
line 20: "HDMI_HPD_N" input
line 21: "USR_LED_1_CTRL" output consumer="apq8016-sbc:green:user1"
line 22: "[I2C1_SDA]" input
line 23: "[I2C1_SCL]" input
line 24: "GPIO-G" input
line 25: "GPIO-H" input
line 26: "[CSI0_MCLK]" input
line 27: "[CSI1_MCLK]" input
line 28: "GPIO-K" input
line 29: "[I2C2_SDA]" input
line 30: "[I2C2_SCL]" input
line 31: "DSI2HDMI_INT_N" input
line 32: "DSI_SW_SEL_APQ" output consumer="pd"
line 33: "GPIO-L" input
line 34: "GPIO-J" input
line 35: "GPIO-I" input
line 36: "GPIO-A" input
line 37: "FORCED_USB_BOOT" input
line 38: "SD_CARD_DET_N" input active-low consumer="cd"
line 39: "[WCSS_BT_SSBI]" input
line 40: "[WCSS_WLAN_DATA_2]" input
line 41: "[WCSS_WLAN_DATA_1]" input
line 42: "[WCSS_WLAN_DATA_0]" input
line 43: "[WCSS_WLAN_SET]" input
line 44: "[WCSS_WLAN_CLK]" input
line 45: "[WCSS_FM_SSBI]" input
line 46: "[WCSS_FM_SDI]" input
line 47: "[WCSS_BT_DAT_CTL]" input
line 48: "[WCSS_BT_DAT_STB]" input
line 49: "NC" input
line 50: "NC" input
line 51: "NC" input
line 52: "NC" input
line 53: "NC" input
line 54: "NC" input
line 55: "NC" input
line 56: "NC" input
line 57: "NC" input
line 58: "NC" input
line 59: "NC" input
line 60: "NC" input
line 61: "NC" input
line 62: "NC" input
line 63: "[CDC_PDM0_CLK]" input
line 64: "[CDC_PDM0_SYNC]" input
line 65: "[CDC_PDM0_TX0]" input
line 66: "[CDC_PDM0_RX0]" input
line 67: "[CDC_PDM0_RX1]" input
line 68: "[CDC_PDM0_RX2]" input
line 69: "GPIO-D" input
line 70: "NC" input
line 71: "NC" input
line 72: "NC" input
line 73: "NC" input
line 74: "NC" input
line 75: "NC" input
line 76: "NC" input
line 77: "NC" input
line 78: "NC" input
line 79: "NC" input
line 80: "BOOT_CONFIG_0" input
line 81: "BOOT_CONFIG_1" input
line 82: "BOOT_CONFIG_2" input
line 83: "BOOT_CONFIG_3" input
line 84: "NC" input
line 85: "NC" input
line 86: "BOOT_CONFIG_5" input
line 87: "NC" input
line 88: "NC" input
line 89: "NC" input
line 90: "NC" input
line 91: "NC" input
line 92: "NC" input
line 93: "NC" input
line 94: "NC" input
line 95: "NC" input
line 96: "NC" input
line 97: "NC" input
line 98: "NC" input
line 99: "NC" input
line 100: "NC" input
line 101: "NC" input
line 102: "NC" input
line 103: "NC" input
line 104: "SSBI_GPS" input
line 105: "NC" input
line 106: "NC" input
line 107: "KEY_VOLP_N" input active-low consumer="Volume Up"
line 108: "NC" input
line 109: "NC" input
line 110: "[LS_EXP_MI2S_WS]" input
line 111: "NC" input
line 112: "NC" input
line 113: "[LS_EXP_MI2S_SCK]" input
line 114: "[LS_EXP_MI2S_DATA0]" input
line 115: "GPIO-E" input
line 116: "NC" input
line 117: "[DSI2HDMI_MI2S_WS]" input
line 118: "[DSI2HDMI_MI2S_SCK]" input
line 119: "[DSI2HDMI_MI2S_DATA0]" input
line 120: "USR_LED_2_CTRL" output consumer="apq8016-sbc:green:user2"
line 121: "SB_HS_ID" input consumer="id"
As you can see, everything works fine. Can you check if the same commands give you errors?
Here's what I get: linaro@linaro:/usr/local$ sudo gpiodetect gpiochip0 [1000000.pinctrl] (122 lines) gpiochip1 [200f000.spmi:pm8916@0:gpios@c00] (4 lines) gpiochip2 [200f000.spmi:pm8916@0:mpps@a000] (4 lines)
linaro@linaro:/usr/local$ sudo gpioinfo -c gpiochip0 gpioinfo: unable to read info for line 0 from gpiochip0: Invalid argument linaro@linaro:/usr/local$
linaro@linaro:/usr/local$ sudo su
root@linaro:/usr/local# gpiodetect gpiochip0 [1000000.pinctrl] (122 lines) gpiochip1 [200f000.spmi:pm8916@0:gpios@c00] (4 lines) gpiochip2 [200f000.spmi:pm8916@0:mpps@a000] (4 lines)
root@linaro:/usr/local# gpioinfo -c gpiochip0 gpioinfo: unable to read info for line 0 from gpiochip0: Invalid argument root@linaro:/usr/local#
Here's the strace for gpioinfo:
Ok, so there's an EINVAL coming out from the kernel, the user-space part looks fine (as long as you have not modified libgpiod?). Are you capable of adding some logs to the kernel driver and recompiling it?
I have not modified libgpiod in any way. For adding logs to the kernel driver, I don't know how to do that. I will need help for that. However, there's not much space left.
linaro@linaro:/var$ df -h Filesystem Size Used Avail Use% Mounted on udev 434M 0 434M 0% /dev tmpfs 92M 7.9M 84M 9% /run /dev/mmcblk0p14 6.7G 5.2G 1.2G 82% / tmpfs 457M 0 457M 0% /dev/shm tmpfs 457M 0 457M 0% /tmp tmpfs 92M 20K 92M 1% /run/user/1000
I tried to upgrade the kernel but I get error messages:
linaro@linaro:/var$ sudo apt modernize-sources The following files need modernizing:
- /etc/apt/sources.list
- /etc/apt/sources.list.d/linaro.list
Modernizing will replace .list files with the new .sources format, add Signed-By values where they can be determined automatically, and save the old files into .list.bak files.
This command supports the 'signed-by' and 'trusted' options. If you have specified other options inside [] brackets, please transfer them manually to the output files; see sources.list(5) for a mapping.
For a simulation, respond N in the following prompt. Rewrite 2 sources? [Y/n] y Modernizing /etc/apt/sources.list...
- Writing /etc/apt/sources.list.d/debian.sources
Modernizing /etc/apt/sources.list.d/linaro.list...
- Writing /etc/apt/sources.list.d/linaro.sources Warning: Could not determine Signed-By for URIs: http://obs.linaro.org/linaro-overlay-sid/sid/, Suites: ./
linaro@linaro:/var$ sudo apt update Hit:1 http://deb.debian.org/debian sid InRelease Ign:2 http://obs.linaro.org/linaro-overlay-sid/sid ./ InRelease Get:3 http://obs.linaro.org/linaro-overlay-sid/sid ./ Release [995 B] Err:4 http://obs.linaro.org/linaro-overlay-sid/sid ./ Release.gpg Sub-process /usr/bin/sqv returned an error code (1), error message is: Signing key on C1E0C2C7E2474F76C17FE8ABC32DA102AD89C2BE is not bound: Policy rejected asymmetric algorithm because: DSA2048 is not considered secure since 2024-02-01T00:00:00Z Fetched 995 B in 2s (544 B/s) 133 packages can be upgraded. Run 'apt list --upgradable' to see them. Warning: An error occurred during the signature verification. The repository is not updated and the previous index files will be used. OpenPGP signature verification failed: http://obs.linaro.org/linaro-overlay-sid/sid ./ Release: Sub-process /usr/bin/sqv returned an error code (1), error message is: Signing key on C1E0C2C7E2474F76C17FE8ABC32DA102AD89C2BE is not bound: Policy rejected asymmetric algorithm because: DSA2048 is not considered secure since 2024-02-01T00:00:00Z Warning: Failed to fetch http://obs.linaro.org/linaro-overlay-sid/sid/./Release.gpg Sub-process /usr/bin/sqv returned an error code (1), error message is: Signing key on C1E0C2C7E2474F76C17FE8ABC32DA102AD89C2BE is not bound: Policy rejected asymmetric algorithm because: DSA2048 is not considered secure since 2024-02-01T00:00:00Z Warning: Some index files failed to download. They have been ignored, or old ones used instead. Notice: Missing Signed-By in the sources.list(5) entry for 'http://obs.linaro.org/linaro-overlay-sid/sid'
Oh, I only now noticed how old your kernel is. It probably doesn't even support libgpiod v2. I can't help you with upgrading, this is outside of the scope of this project but I'm sure once you do, all will work fine. I test linux-next on the same board.
Thanks for your help! What kernel version should I look for upgrading the distro?
This board is supported in mainline so you're good with any recent stable release really.