Add Bluetooth overlays #3682

gentoo-root · 2020-06-21T16:19:57Z

As a follow-up for #3675, this pull request adds device tree overlays to give users an option to configure Bluetooth without hciattach/btattach, and changes the defconfigs to make this way work.

pelwell · 2020-06-21T16:40:41Z

All overlays require documentation in the README file - if you add that now I can review it all together.

macmpi · 2020-06-21T17:17:15Z

Nice.
You may want to add reference to PiZeroW in bt-overlay.dts , and also do similar for bcm2708 (bcm2835 in upstream DTBs).
@pelwell could that eventually be merged into 5.4.y too? That would really be sweet.

pelwell · 2020-06-21T17:19:58Z

Anything merged is eventually ported to all current branches (where possible).

gentoo-root · 2020-06-21T17:31:28Z

You may want to add reference to PiZeroW in bt-overlay.dts

Sure, I can mention it. Just to clarify (because I don't have one for tests), does Zero W support flow control (so that bt-overlay.dts is the right one)?

also do similar for bcm2708 (bcm2835 in upstream DTBs).

Sorry, I didn't get it... Do you mean I need to add some different overlay for bcm2708?

pelwell · 2020-06-21T17:54:07Z

I have no problem with what you've done so far, but I think we can do better from a user's perspective. I don't like the fact that they have to know whether their Pi supports BT flow control - it would be better that enabling Bluetooth in a common way (i.e. one overlay, or one parameter) automatically chose the default baud rate, but with an override to change it.

The serdev enumeration that enables the Bluetooth support checks for enabled nodes, which means the bluetooth nodes can appear in the base DTBs by default, with the correct baud rates, but disabled, with an overlay or (better) dtparam to enable it. If we ever switch over so that this method is used by default we could just change the default state and keep the parameter as a way to disable it.

What do you think?

gentoo-root · 2020-06-21T19:31:13Z

Sounds great! Basically, I can add the bluetooth nodes to the main trees, disabled by default, and with correct baud rates for different boards (i.e. 3000000 for Pi4, 921600 for Pi3), and a dtparam to enable Bluetooth — I think, I can do that.

However, there is this Pi3 rev 1.2/1.3 difference in flow control support, and both of them share the same device tree. Do you have an idea how to handle it with your approach? I can only think of another dtparam to force baud rate, but it means the user will have to set it manually on Pi3 rev 1.3.

pelwell · 2020-06-21T19:35:57Z

Hmm - okay then, in that case it makes sense for the firmware to set a sensible baud rate using the parameter before any user settings are applied. Until the firmware is updated, users of the 3B <= rev 1.2 will have to set the baud rate manually.

pelwell · 2020-06-21T19:37:13Z

Which (I think) means the bluetooth node just needs to go in bcm270x-rpi.dtsi.

macmpi · 2020-06-26T17:49:45Z

What's the final take on this?
bluetooth node in bcm270x-rpi.dtsi, and dtparam to activate & eventually set custom baud rate (particularly for Pi3 rev 1.2)?

(@gentoo-root yes indeed, PiZeroW does support HW flowcontrol)

The next patch adds a device tree overlay for Bluetooth. The Bluetooth device node is a child of uart0 (pl011). The children of pl011 are not registered as platform devices by of_platform_bus_create, because they fall into `of_device_is_compatible(bus, "arm,primecell")` check. These children are registered by of_serdev_register_devices, called through this chain of calls: - uart_add_one_port (drivers/tty/serial/amba-pl011.c) - tty_port_register_device_attr_serdev - serdev_tty_port_register - serdev_controller_add - of_serdev_register_devices serdev_tty_port_register depends on CONFIG_SERIAL_DEV_CTRL_TTYPORT, which in turn depends on CONFIG_SERIAL_DEV_BUS=y. This patch modifies the defconfigs of Raspberry Pi devices to set these options and allow to bind drivers to subnodes of UART devices that can be added by device tree overlays. Signed-off-by: Maxim Mikityanskiy <[email protected]>

gentoo-root · 2020-06-27T09:54:31Z

bluetooth node in bcm270x-rpi.dtsi

bcm270x-rpi.dtsi is too generic, it's included by the boards without Bluetooth, too. I was planning to patch the concrete boards with Bluetooth: bcm2708-rpi-zero-w.dts, bcm2710-rpi-3-b.dts, bcm2710-rpi-3-b-plus.dts, bcm2711-rpi-4-b.dts (I hope the list is complete), because *.dtsi files are always shared with some non-Bluetooth boards. Probably it makes sense to add a new bcm27xx-rpi-bt.dtsi and include it from those four *.dts files.

dtparam to activate & eventually set custom baud rate (particularly for Pi3 rev 1.2)?

Yes.

BTW, adding the bluetooth node to the main tree will require changes to disable-bt-overlay.dts and miniuart-bt-overlay.dts.

I'm on it currently.

gentoo-root · 2020-06-27T11:54:28Z

I updated the patch, tested the following combinations on Pi3B rev 1.2 and got the expected results:

# Probes at 3 Mbaud.
dtparam=bluetooth=on

# Probes at 921600 baud.
dtparam=bluetooth=on
dtparam=bluetooth_baudrate=921600

# Doesn't probe.
dtparam=bluetooth=on
dtparam=bluetooth_baudrate=921600
dtoverlay=disable-bt

# Doesn't autoprobe; `btattach -B /dev/ttyS0 -P bcm -S 460800 -N` works.
dtparam=bluetooth=on
dtparam=bluetooth_baudrate=921600
dtoverlay=miniuart-bt

# Probes at 460800 on miniUART, /dev/ttyS0 doesn't appear.
dtoverlay=miniuart-bt,probe=on

pelwell

Apart from addressing the line comments I'm going to need some entries in the README file for the new parameter, but we're nearly there.

arch/arm/boot/dts/bcm2708-rpi-zero-w.dts

arch/arm/boot/dts/bcm27xx-rpi-bt.dtsi

pelwell · 2020-06-30T13:19:49Z

arch/arm/boot/dts/overlays/miniuart-bt-overlay.dts

 		target-path = "/aliases";
 		__overlay__ {
 			serial0 = "/soc/serial@7e201000";
 			serial1 = "/soc/serial@7e215040";
 		};
 	};
+
+	__overrides__ {
+		probe = <&minibt>,"status";


probe is a bit vague - I suggest re-using the same name used with the base DTBS, e.g. knlbt.

arch/arm/configs/bcm2709_defconfig

gentoo-root · 2020-06-30T20:43:23Z

I updated the patch, addressing all the comments above. I'll retest it one more time after we are done with the review.

arch/arm/boot/dts/bcm2708-rpi-bt.dtsi

Add device tree nodes for Bluetooth on supported Raspberry Pi boards. It's disabled by default and can be enabled by `krnbt=on` dtparam. It's an alternative way of configuring Bluetooth, as compared to hciattach or btattach. When the dtparam is enabled, the Bluetooth driver is probed automatically and doesn't require any additional bring-up scripts. Note that Raspberry Pi 3 B rev 1.2 doesn't have the required hardware flow control pins of UART0 connected to the Bluetooth module, so the user should decrease the baudrate by passing `krnbt_baudrate=921600` dtparam to make it more stable. It resembles the behavior of the btuart script from Raspbian. The miniuart-bt overlay was modified to support Bluetooth probing with device tree, too. It's disabled by default and can be enabled by `krnbt=on` parameter of the miniuart-bt overlay. Signed-off-by: Maxim Mikityanskiy <[email protected]>

pelwell · 2020-06-30T21:48:14Z

That looks good - I'll test it in the morning.

pelwell · 2020-07-01T10:45:49Z

Thanks - that works as expected. It doesn't solve the problem of Pis which haven't had their BDADDR written to OTP, but as this is an opt-in change I can live with that.

macmpi · 2020-07-01T10:54:31Z

Great!Tthanks so much @gentoo-root and @pelwell
Phil, can merge in 5.4.y too, please?

pelwell · 2020-07-01T11:14:28Z

Your wish is my command.

kernel: drm/vc4: Allow interlaced HDMI modes from FKMS See: raspberrypi/linux#3698 kernel: Isp driver fixes See: raspberrypi/linux#3695 kernel: Add Bluetooth overlays See: raspberrypi/linux#3682 firmware: arm_loader: Allow interlaced HDMI modes from FKMS See: raspberrypi/linux#3698 firmware: arm_loader: Limit rather than reject boosts with disable_auto_turbo firmware: i2c: Clearing the TA bit may time out See: #1422 firmware: arm_loader: Add an accelerated memmove firmware: arm_loader: memmove kernel to preferred text_offset See: #1421 firmware: filesystem: Fix GPT regression on USB after SD fix See: #1420 firmware: bootloader: Some tweaks for LED, UART, USB timeouts

kernel: drm/vc4: Allow interlaced HDMI modes from FKMS See: raspberrypi/linux#3698 kernel: Isp driver fixes See: raspberrypi/linux#3695 kernel: Add Bluetooth overlays See: raspberrypi/linux#3682 firmware: arm_loader: Allow interlaced HDMI modes from FKMS See: raspberrypi/linux#3698 firmware: arm_loader: Limit rather than reject boosts with disable_auto_turbo firmware: i2c: Clearing the TA bit may time out See: raspberrypi/firmware#1422 firmware: arm_loader: Add an accelerated memmove firmware: arm_loader: memmove kernel to preferred text_offset See: raspberrypi/firmware#1421 firmware: filesystem: Fix GPT regression on USB after SD fix See: raspberrypi/firmware#1420 firmware: bootloader: Some tweaks for LED, UART, USB timeouts

pelwell · 2020-07-02T15:34:56Z

Just a note to say that the krnbt parameter of the miniuart-bt overlay won't apply as it was written - it was an overlay parameter that tried to directly modify a node in the base DTB, and that's not currently supported. The workaround is to add another fragment, which can be initially empty, targetting the node in the base DTB, and modify the parameter to update the fragment. The fixed version is in rpi-5.4.y now (and will be copied to the others...) but just missed the firmware release.

Having said that, I can't make miniuart-bt,kernbt work at the moment, for reasons I haven't figured out. The kernel claims the uart1 (/dev/ttyS0 disappears) and attempts to bring up the HCI interface, but it times out on the baudrate change:

[    5.716118] Bluetooth: HCI device and connection manager initialized
[    5.716143] Bluetooth: HCI socket layer initialized
[    5.751398] Bluetooth: HCI UART driver ver 2.3
[    5.751417] Bluetooth: HCI UART protocol H4 registered
[    5.751507] Bluetooth: HCI UART protocol Three-wire (H5) registered
[    5.751857] Bluetooth: HCI UART protocol Broadcom registered
[    5.753400] hci_uart_bcm serial0-0: serial0-0 supply vbat not found, using dummy regulator
[    5.753529] hci_uart_bcm serial0-0: serial0-0 supply vddio not found, using dummy regulator
[    8.031745] Bluetooth: hci0: command 0xfc18 tx timeout
[   16.095674] Bluetooth: hci0: BCM: failed to write update baudrate (-110)
[   16.095682] Bluetooth: hci0: Failed to set baudrate
[   18.111671] Bluetooth: hci0: command 0x0c03 tx timeout
[   26.335699] Bluetooth: hci0: BCM: Reset failed (-110)

pelwell · 2020-07-29T16:40:45Z

This change has caused additional serial ports to no longer appear as character devices - see https://github.com/raspberrypi/firmware/issues/1438 for the report.
Do you know how to solve that problem without reverting this PR?

gearhead · 2020-07-31T00:12:44Z

Thanks for doing this. It is a big help. Are there specific kernel config parameters which need to be set to make this work? Any specific packages which need to be installed?
I confirm it works for my PiZero and a B3 with the current 5.4.51-1 kernel on Arch Arm for armv6 and armv7. Trying to get it going on aarch64 and have had no joy, yet. Re-building 5.4.51-1 for it right now. To get it to work on my B3, I had to install firmware-brcm43xx. This package is not available for armv6 on arch, though, but it still works on my PiZero.
Update: Re-built kernel with slightly different configs and still no onboard bluetooth.
Do I need to do something with the cmdline.txt?

gearhead · 2020-08-02T23:42:27Z

Fixed it. I meandered around the kernel config and changed a bunch of things but did not change it. I then went and grabbed the raspberry kernel source from Rpi and made a new config and rebuilt and now this config.txt setting works on aarch64 as well.

popcornmix force-pushed the rpi-5.7.y branch from 0551425 to b21bf15 Compare June 26, 2020 13:15

pelwell requested changes Jun 30, 2020

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pelwell reviewed Jun 30, 2020

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arch/arm/boot/dts/bcm2708-rpi-bt.dtsi Outdated Show resolved Hide resolved

pelwell approved these changes Jul 1, 2020

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pelwell merged commit 856dd81 into raspberrypi:rpi-5.7.y Jul 1, 2020

macmpi mentioned this pull request Jul 1, 2020

On-board Bluetooth: loading firmware with devicetree #3459

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macmpi mentioned this pull request Jul 15, 2020

On Pi3 B and B+ choppy sound arkq/bluez-alsa#205

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Add Bluetooth overlays #3682

Add Bluetooth overlays #3682

gentoo-root commented Jun 21, 2020

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Add Bluetooth overlays #3682

Add Bluetooth overlays #3682

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