Bluetooth is not autodetected with device tree (bcm2837-rpi-3-b.dtb) on Raspberry Pi 3 #3675
Description
Is this the right place for my bug report?
I hope so, because it's kernel-related and Raspberry Pi-specific.
Describe the bug
The upstream device tree (bcm2837-rpi-3-b.dtb) attempts to configure Bluetooth:
/* uart0 communicates with the BT module */
&uart0 {
pinctrl-names = "default";
pinctrl-0 = <&uart0_gpio32 &gpclk2_gpio43>;
status = "okay";
bluetooth {
compatible = "brcm,bcm43438-bt";
max-speed = <2000000>;
shutdown-gpios = <&expgpio 0 GPIO_ACTIVE_HIGH>;
};
};
However, the code in drivers/of/platform.c skips the bluetooth subsection, because uart0 is defined in bcm283x.dtsi as follows:
uart0: serial@7e201000 {
compatible = "arm,pl011", "arm,primecell";
reg = <0x7e201000 0x200>;
interrupts = <2 25>;
clocks = <&clocks BCM2835_CLOCK_UART>,
<&clocks BCM2835_CLOCK_VPU>;
clock-names = "uartclk", "apb_pclk";
arm,primecell-periphid = <0x00241011>;
};
It contains "arm,primecell" in compatible, which makes the enumeration code in drivers/of/platform.c to return early and skip enumerating children of uart0, i.e. the bluetooth node. As a result, hci_uart is not autoloaded by udev, and when loaded manually, it doesn't autodetect the Bluetooth hardware, so I need to run btattach or hciattach manually.
Tested on both this kernel (built from the 5.7.y branch) and the upstream kernel (5.7.2).
To reproduce
- Have bluez installed. Disable
hciuart.serviceor any other scripts that runhciattachorbtattachon boot. - Set
device_tree=dtbs/broadcom/bcm2837-rpi-3-b.dtbin/boot/config.txt. - Boot the system.
Expected behaviour
Bluetooth adaptor is probed with device tree and is visible in the system (e.g., under /sys/class/bluetooth/hci0).
Actual behaviour
/sys/class/bluetooth is empty, bluetoothd doesn't autostart, no Bluetooth functionality in the system.
System
Sorry, I use a custom distribution, so I don't have many of the requested commands, but I believe the information below should be enough, the rest doesn't seem relevant.
Copy and paste the results of the raspinfo command in to this section. Alternatively, copy and paste a pastebin link, or add answers to the following questions:
- Which model of Raspberry Pi? Pi3B.
- Which OS and version (
cat /etc/rpi-issue)? Custom Linux distribution. - Which firmware version (
vcgencmd version)? - Which kernel version (
uname -a)? Upstream kernel 5.7.2 and raspberry kernel from branch 5.7.y.
Logs
dmesg part with debug output enabled in drivers/of/platform.c:
[ 0.105038] Serial: AMBA PL011 UART driver
[ 0.105406] OF: of_platform_populate()
[ 0.105428] OF: starting at:
[ 0.105456] OF: of_platform_bus_create() - skipping /system, no compatible prop
[ 0.105480] OF: of_platform_bus_create() - skipping /axi, no compatible prop
[ 0.105505] OF: of_platform_bus_create() - skipping /aliases, no compatible prop
[ 0.105805] OF: of_platform_bus_create() - skipping /reserved-memory, no compatible prop
[ 0.105830] OF: of_platform_bus_create() - skipping /thermal-zones, no compatible prop
[ 0.106069] OF: create child: /soc/timer@7e003000
[ 0.107054] OF: create child: /soc/txp@7e004000
[ 0.107617] OF: create child: /soc/cprman@7e101000
[ 0.108001] OF: create child: /soc/mailbox@7e00b880
[ 0.108578] OF: create child: /soc/gpio@7e200000
[ 0.109561] OF: create child: /soc/serial@7e201000
[ 0.109593] OF: Creating amba device /soc/serial@7e201000
[ 0.110384] OF: create child: /soc/mmc@7e202000
[ 0.110945] OF: create child: /soc/i2s@7e203000
[ 0.110984] OF: create child: /soc/spi@7e204000
[ 0.111022] OF: create child: /soc/i2c@7e205000
[ 0.111578] OF: create child: /soc/dpi@7e208000
[ 0.111617] OF: create child: /soc/dsi@7e209000
[ 0.111655] OF: create child: /soc/aux@7e215000
[ 0.112049] OF: create child: /soc/serial@7e215040
[ 0.112617] OF: create child: /soc/spi@7e215080
[ 0.112656] OF: create child: /soc/spi@7e2150c0
[ 0.112694] OF: create child: /soc/pwm@7e20c000
[ 0.113089] OF: create child: /soc/sdhci@7e300000
[ 0.113647] OF: create child: /soc/hvs@7e400000
[ 0.114182] OF: create child: /soc/dsi@7e700000
[ 0.114222] OF: create child: /soc/i2c@7e804000
[ 0.114805] OF: create child: /soc/vec@7e806000
[ 0.115330] OF: create child: /soc/usb@7e980000
[ 0.115899] OF: create child: /soc/dma@7e007000
[ 0.118636] OF: create child: /soc/interrupt-controller@7e00b200
[ 0.118674] OF: create child: /soc/watchdog@7e100000
[ 0.119157] OF: create child: /soc/rng@7e104000
[ 0.119720] OF: create child: /soc/pixelvalve@7e206000
[ 0.120246] OF: create child: /soc/pixelvalve@7e207000
[ 0.120820] OF: create child: /soc/thermal@7e212000
[ 0.121205] OF: create child: /soc/i2c@7e805000
[ 0.121759] OF: create child: /soc/pixelvalve@7e807000
[ 0.122295] OF: create child: /soc/hdmi@7e902000
[ 0.123099] OF: create child: /soc/v3d@7ec00000
[ 0.123661] OF: create child: /soc/gpu
[ 0.123925] OF: create child: /soc/local_intc@40000000
[ 0.123965] OF: create child: /soc/firmware
[ 0.124249] OF: create child: /soc/firmware/gpio
[ 0.124546] OF: create child: /soc/power
[ 0.124865] OF: create child: /soc/mailbox@7e00b840
[ 0.125413] OF: of_platform_bus_create() - skipping /clocks, no compatible prop
[ 0.126712] OF: of_platform_bus_create() - skipping /cpus, no compatible prop
[ 0.126963] OF: of_platform_bus_create() - skipping /memory@0, no compatible prop
As we see, it doesn't traverse the children of /soc/serial@7e201000, instead it creates an AMBA device.
Additional context
It sounds weird that there is a guy who claims that device tree autoprobing of Bluetooth worked for him: https://gist.github.com/shenghaoyang/92e6dd65b9f0cc736a419f3e640663c2. He basically adds a part of the upstream device tree as an overlay for the raspberry device tree (bcm2710-rpi-3-b.dtb). This approach hasn't worked for me either, for the same reason explained above.