Subject: Re: [PATCHv2] Description of the realtek bluetooth device tree hooks
To:     Rob Herring <robh@kernel.org>
Cc:     marcel@holtmann.org, johan.hedberg@gmail.com, mark.rutland@arm.com,
        linux-bluetooth@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org
References: <20181229115513.31153-1-beagleboard@davidjohnsummers.uk>
 <20190103163538.6575-1-beagleboard@davidjohnsummers.uk>
 <20190111163420.GA20311@bogus>
From:   David Summers <beagleboard@davidjohnsummers.uk>
Message-ID: <1308b7df-9f09-c46e-e740-131bd1c42fef@davidjohnsummers.uk>
Date:   Sat, 12 Jan 2019 15:00:17 +0000
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Thanks Rob,

I'll hopefully make those changes this weekend, and resubmit - just so 
next weekend can move onto the device tree.

Oh yes, on the "-bluetooth" or "-bt"; as these devices have both and 
sdio input for wifi, and uart for bluetooth; I guess they will need to 
be listed twice in a device tree, both under uart and sdio. Now as both 
these parts of the device tree will want to specify the driver used, and 
the driver is different for bluetooth and for wifi - doesn't that mean 
we should specify compatible differently? Otherwise how will the kernel 
know which driver to load for wifi and which for bluetooth?

So question is am I missing something here, and this could be simplified?

On the interrupts, GPIO control lines, power supplies, etc, on the ASUS 
code that I'm basing the patches on (for Tinker Board S) - these bits 
are freestanding in the device tree, and mainly go in with the wifi 
patch (and not bluetooth). I'll put some though into how this is best 
arranged when going mainline. I think if I'm honest, if I wait to get 
all these extras in the documentation, this will only get settled when I 
get the wifi into the device tree - as problem is more natural there. 
This though would delay the bluetooth patch probably a month. I'd prefer 
to get something out there - even if I have to return later to tidy the 
documentation.

Regards, and thanks for the helpful comments.

David.


On 11/01/2019 16:34, Rob Herring wrote:
> On Thu, Jan 03, 2019 at 04:35:37PM +0000, David Summers wrote:
>> This adds the desrciption file that describes the hooks for the
>> realtek bluetooth serial devices, as needed to refer to the interface
>> in the device tree.
> Please follow conventions for patch subjects. 'git log --oneline
> --no-merges -- path/to/file' usually gives a good clue. In this case,
> something like:
>
> dt-bindings: net: Add Realtek serial bluetooth binding
>
>> Signed-off-by: David Summers <beagleboard@davidjohnsummers.uk>
>> ---
>>   .../bindings/net/realtek-bluetooth-serial.txt | 28 +++++++++++++++++++
>>   1 file changed, 28 insertions(+)
>>   create mode 100644 Documentation/devicetree/bindings/net/realtek-bluetooth-serial.txt
>>
>> diff --git a/Documentation/devicetree/bindings/net/realtek-bluetooth-serial.txt b/Documentation/devicetree/bindings/net/realtek-bluetooth-serial.txt
>> new file mode 100644
>> index 000000000000..0aabca1fc002
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/net/realtek-bluetooth-serial.txt
>> @@ -0,0 +1,28 @@
>> +Realtek bluetooth devices connected via a UART
>> +
>> +- compatible: should be "realtek,<name>-bluetooth"
>> +  except for "realtek,trl8761atv" - which only has a serial bluetooth connection
>> +       "realtek,rtl8723as-bluetooth"
>> +       "realtek,rtl8723bs-bluetooth"
>> +       "realtek,rtl8723ds-bluetooth"
>> +       "realtek,rtl8761atv"
>> +       "realtek,rtl8821as-bluetooth"
>> +       "realtek,rtl8821cs-bluetooth"
>> +       "realtek,rtl8822bs-bluetooth"
> Arguably, '-bluetooth' is not necessary as nothing else is attached to
> the serial port. At least shorten it to '-bt'.
>
>> +- These device are bluetooth devices, that connect via a uart
> s/device/devices/
>
>> +- all devices (except for rtl8761atv) are also wifi devices, this is connected
>> +  seperatly via sdio - and is not covered by this compatible node
> Really, this should be up above the property list in a description of
> the device(s).
>
>> +- ideally these will be referenced in a device tree serial node via serdev
> Not ideally, but it is only valid for this to be a child of a UART.
>
> serdev is a kernel thing, and shouldn't be part of the binding doc.
>
>> + http://events17.linuxfoundation.org/sites/events/files/slides/serdev-elce-2017-2.pdf
> Useful, but again, not part of this binding.
>
> There's no interrupts, GPIO control lines, power supplies, etc. for
> these chips? The binding should be complete even if your platform
> doesn't need these.
>
>> +
>> +Example:
>> +
>> +&uart0 {
>> +	status = "okay";
> Don't show status in examples.
>
>> +       	pinctrl-0 = <&uart0_xfer>, <&uart0_cts>;
>> +       	bluetooth {
>> +               	  compatible = "realtek,rtl8723bs-bluetooth";
>> +       	};
> Mixed tabs and spaces. Use tabs.
>
>> +};
>> +
>> +this ensures that the bluetooth device is tied to the correct uart
>> -- 
>> beagleboard@davidjohnsummers.uk
>>