On 17/02/2019 21:05, Stefan Wahren wrote:
Hi David,
David Summers <beagleboard@xxxxxxxxxxxxxxxxxxx> hat am 17. Februar 2019 um 13:15 geschrieben:
This patch is to add Bluetooth to the ASUS Tinker Board (S) device
tree.
This patch is more contraversal - so probably view it as a request for
comments.
The reason behind this, is this patch does not currently set Bluetooth
working on the these boards. The problem is that the
bluetooth/hci_h5.c driver, that is used for Realtek serial devices,
depends on ACPI. Unfortantly ACPI can not be enabled on armv7 machines
such as the TB(S). And so the kernel module for the RTL8723BS
Bluetooth can not be loaded.
However this patch is believed to be an accurate description of the
Tinker Board (S) wiring. It is strongly based on the ASUS patch:
https://github.com/TinkerBoard/debian_kernel/commit/6a3128ade33f758887048578ada61a4b7ab8e678
As the Bluetooth is connected via a UART and this is wired into uart0,
this has been described as a SerDev.
The ASUS patch mentions the UART_CTS, but not the _RTS. Now as the
RTL8723BS has both CTS and RTS on the uart, it has been assumed both
are wired into uart0 on the cpu.
which would be very strange, because we could use H4 instead of H5.
Well the bluetooth maintainer said it was hci_h5.
The device is BT4.0 and that under Volume 4 HCI, Part D - 2 wire UART
Transport Layer, in section 11.2 says that Hardware flow control may be
used.
Also if you check what ASUS did:
https://github.com/TinkerBoard/debian_kernel/commit/5106d9486cf1c2bad4f701611f51a526191c56ad
They added H5 code to the hci_h4.c, seems strange but thats what they
said they did.
Now maybe the RTL8723BS could work with the UART Transport Layer, but
that hasn't been done yet. 3 wire has some overhead, but it doesn't look
like much.
To my mind though it down to the bluetooth Maintainer - so CCing Marcel
Holtmann in ...
The Bluetooth connection has several wake up pins both device and host
and a reset pin. The wiring of these has been described; however how
the kernel driver will use these isn't clear. E.g. should HOST_WAKE be
an interupt?
The main reason for asking for comments, is that when it comes time to
make the changes to the bluetooth uart code, and add compatible flags,
robh has indicated that this will only be accepted with a valid
example. So the code below is that example. So I would like comments
that this approach is valid, which can be used when the later
submission comes.
Asking for comment should be mark with RFC in the patch subject.
OOps my mistake.
Signed-off-by: David Summers <beagleboard@xxxxxxxxxxxxxxxxxxx>
---
arch/arm/boot/dts/rk3288-tinker.dtsi | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/arch/arm/boot/dts/rk3288-tinker.dtsi b/arch/arm/boot/dts/rk3288-tinker.dtsi
index e1796f340eef..931b4c652fdc 100644
--- a/arch/arm/boot/dts/rk3288-tinker.dtsi
+++ b/arch/arm/boot/dts/rk3288-tinker.dtsi
@@ -481,6 +481,17 @@
&uart0 {
status = "okay";
+ pinctrl-names = "default";
+ pinctrl-0 = <&uart0_xfer>, <&uart0_cts>, <&uart0_rts>;
+
+ bluetooth {
+ clocks = <&rk808 RK808_CLKOUT1>;
As we already linked the RK808 clock in the sdio pwrseq, we shouldn't do this here again.
+ reset-gpios = <&gpio4 RK_PD5 GPIO_ACTIVE_LOW>;
reset-gpios isn't compatible to hci_h5, please use my preliminary dt-binding
+ device-wake-gpios = <&gpio4 RK_PD2 GPIO_ACTIVE_HIGH>;
+ host-wake-gpios = <&gpio4 RK_PD7 GPIO_ACTIVE_HIGH>;
AFAIK hci_h5 doesn't support host-wake yet. So if you want to keep for the future we should make a comment.
+ vcc-18-supply = <&vcc_18>;
+ vcc-io-supply = <&vcc_io>;
Please drop these as the driver doesn't use it and it's already linked in the sdio pwrseq.
Thanks Stefan
+ };
[1] - https://gist.github.com/lategoodbye/79bac99d4f1158a719a48ea3c45eb7f1#file-0002-dt-bindings-add-support-for-realtek-bluetooth-serial-patch
Sorry I disagree here.
Last time I posted an example patch like this robh said clearly that
these should give clocks, power, etc:
https://www.spinics.net/lists/linux-bluetooth/msg78545.html
https://www.spinics.net/lists/linux-bluetooth/msg78585.html
<https://www.spinics.net/lists/linux-bluetooth/msg78585.html>
and as he is maintainer he wins.
I can understand Robs position, device tree are for describing hardware,
they aren't primarily for helping code to load. Yes that is a second
effect, its so it knows what is in the hardware. In this case what if
someone wanted Bluetooth, but not WiFi - then the Bluetooth should know
what power and clocks are needed. Now that the driver doesn't understand
these things is secondary. Maybe that will be cured in future?
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