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

Hi Loic,

Loic Poulain [off-list ref] hat am 14. August 2017 um 19:32 ges=

chrieben:

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On 14/08/2017 18:02, Marcel Holtmann wrote:

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Hi Loic,

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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/bcm2837-rpi-3-b.dts

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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";

This is an unrelated change. "earlyprintk" is arm32 specific and onl=

y

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works with a kernel built with a specific uart type and address. Als=

o,

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stdout-path property is preferred to set the default over "console=

=E2=80=9D.

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I'm going to use stdout-path according to your comment.
However one of the goals was to overwrite the bcm283x.dtsi bootargs,
I assume the same comment apply on the dtsi (stdpath usage /earlyprint=

k)

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which should require update too.

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the whole fun with the serial console on the rPI3 and the bt-miniuart=

 overlay is something we should solve now. What is the upstream story on th=
is since the config.txt and everything around it is confusing and also misl=
eading since it relies on a Raspbian userspace.

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Do we need to the kernel and init to stay away from the ttyAMA0 to av=

oid confusing the BT chip? As I mentioned earlier, I can not even get a Fed=
ora 26 with hciattach or btattach to work.

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It is also possible to mux the auxiliary mini UART to drive the Blueto=

oth

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controller in order to keep ttyAMA0 as the "legacy" RPi ext-uart/conso=

le,

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however SoC spec says that this mini UART is intented to be used mainl=

y as

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a console due to shallow FIFOs and no DMA.

what upstream kernel tree did you test this with? On a Fedora 26 kernel=

 (now 4.12 based), I still do not have the Bluetooth hardware working.

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Regards

Marcel

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I built kernel, modules and dtb from a bluetooth-next tree (4.12 and=20
4.13-rc3).
Using 32-bit multi_v7_defconfig + some additional confs to enable=20
miniuart (BCM2835AUX...) for console.
I push this on a raspbian image.
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my boot/config.txt is very simple (no overlay):
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kernel=3DzImage
device_tree=3Dbcm2837-rpi-3-b.dtb
# hack for miniuart serial clock
core_freq=3D250
dtparam=3Daudio=3Don
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since the BCM2837 is a 64 bit platform, could you please test also this cas=
e?

Thanks
Stefan

Regards,
Loic
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