Re: [PATCH v3 2/3] ARM: dts: bcm2837-rpi-3-b: Add bcm43438 as serial slave

On Tue, Aug 15, 2017 at 8:06 AM, Marcel Holtmann [off-list ref] wrot=
e:

Hi Rob,

quoted

Add BCM43438 as a slave device of uart0 (pl011/ttyAMA0).
This allows to automatically insert the bcm43438 to the bluetooth
subsystem instead of relying on userspace helpers (hciattach).

Overwrite bootargs to use 8250 aux uart (ttyS0) as console instead
of pl011/ttyAMA0.

Signed-off-by: Loic Poulain <redacted>
---
v2: dt-bindings as separate patch
    rebase on upcoming pi3 dts changes
v3: changes in bcm serdev drivers:
    name refactoring and additional comments
    Add generic host_set_baudrate method
    Use agnostic device_property_read

arch/arm/boot/dts/bcm2837-rpi-3-b.dts | 10 ++++++++++
1 file changed, 10 insertions(+)

diff --git a/arch/arm/boot/dts/bcm2837-rpi-3-b.dts b/arch/arm/boot/dts/b=

cm2837-rpi-3-b.dts

quoted

index 20725ca..5abc1df 100644

--- a/arch/arm/boot/dts/bcm2837-rpi-3-b.dts
+++ b/arch/arm/boot/dts/bcm2837-rpi-3-b.dts

@@ -8,6 +8,11 @@
      compatible =3D "raspberrypi,3-model-b", "brcm,bcm2837";
      model =3D "Raspberry Pi 3 Model B";

+     chosen {
+             /* 8250 auxiliar UART instead of pl011 */
+             bootargs =3D "earlyprintk console=3DttyS0,115200";
+     };
+
      memory {
              reg =3D <0 0x40000000>;
      };

@@ -24,6 +29,11 @@
      pinctrl-names =3D "default";
      pinctrl-0 =3D <&uart0_gpio32 &gpclk2_gpio43>;
      status =3D "okay";
+
+     bluetooth {
+             compatible =3D "brcm,bcm43438-bt";
+             max-speed =3D <921600>;
+     };

};

I know that hci_ll.c DT entry also uses max-speed for the naming. Is this=

 something common we should be doing? Essentially it is not really max-spee=
d. It is the operational speed that we are configuring. There is no down ne=
gotiation ongoing. Does it make sense to use oper-speed instead?

max-speed is correct to use. By default, a driver should know the max
speed of a device (implied by the compatible). The DT property is only
for when there is some host or board limitation as this case seems to
be.

Are we otherwise fine with compatible string naming?

Yes.

Rob

Loic, the hciattach examples list 3000000 as operational speed. Any reaso=

n why we should limit it?

Regards

Marcel