linux-kernel - Re: [PATCH RFC v4 07/10] dt-bindings: net: add binding for QCA7000 UART

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Message-ID: <9a094176-ebe7-d906-ca9c-967285e53b07@i2se.com>
Date:   Tue, 28 Mar 2017 18:18:03 +0200
From:   Stefan Wahren <stefan.wahren@...e.com>
To:     Rob Herring <robh+dt@...nel.org>
Cc:     Mark Rutland <mark.rutland@....com>,
        "David S. Miller" <davem@...emloft.net>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jslaby@...e.com>,
        Marcel Holtmann <marcel@...tmann.org>,
        Sebastian Reichel <sre@...nel.org>,
        netdev <netdev@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-serial@...r.kernel.org" <linux-serial@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH RFC v4 07/10] dt-bindings: net: add binding for QCA7000
 UART

Am 27.03.2017 um 22:30 schrieb Rob Herring:
> On Mon, Mar 27, 2017 at 8:37 AM, Stefan Wahren <stefan.wahren@...e.com> wrote:
>> This is the serdev binding for the QCA7000 UART driver (Ethernet over UART).
>>
>> Signed-off-by: Stefan Wahren <stefan.wahren@...e.com>
>> ---
>>
>> According to this binding are still some questions:
>>
>> Where should be the optional hardware flow control defined (at master or slave side)?
> Probably should be in the slave side. We already have uart-has-rtscts
> and rts/cts-gpios for the UART. Those mean we have RTS/CTS, but not
> necessarily that we want to enable them.
>
> In many cases, the driver may know what it needs.

Like all the other UART settings the hardware flow control can be
configured in the QCA7000 firmware and the driver can't detect it.

Property suggestion for the slave side:

use-rtscts


>
>> Is it okay to have two bindings (qca-qca7000-spi and qca-qca7000-uart) or should they be merged?
> Are they mutually-exclusive or both are used at the same time?

They are mutually-exclusive because they use the same pins.

>  What
> are the dependencies between the interfaces?

Except they uses the same pins of the QCA7000, i can't see any dependency.

>
>>
>>  .../devicetree/bindings/net/qca-qca7000-uart.txt   | 31 ++++++++++++++++++++++
>>  1 file changed, 31 insertions(+)
>>  create mode 100644 Documentation/devicetree/bindings/net/qca-qca7000-uart.txt
>>
>> diff --git a/Documentation/devicetree/bindings/net/qca-qca7000-uart.txt b/Documentation/devicetree/bindings/net/qca-qca7000-uart.txt
>> new file mode 100644
>> index 0000000..f2e0450
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/net/qca-qca7000-uart.txt
>> @@ -0,0 +1,31 @@
>> +* Qualcomm QCA7000 (Ethernet over UART protocol)
>> +
>> +Note: This binding applies in case the QCA7000 is configured as a
>> +UART slave device. It is possible to preconfigure the UART settings
>> +of the QCA7000 firmware, which can't be changed during runtime.
>> +
>> +Required properties:
>> +- compatible        : Should be "qca,qca7000-uart"
>> +
>> +Optional properties:
>> +- local-mac-address : 6 bytes, Specifies MAC address
> The description can be "see ./ethernet.txt"
>
>> +- current-speed     : Specifies the serial device speed in
>> +                     bits per second (default = 115200), which is
>> +                     predefined by the QCA7000 firmware configuration
> Add this to the slave binding doc with some caveats as to when this
> should or should not be used as we discussed.
>
> Rob