From: Rob Herring <robh@kernel.org>
To: Michael Walle <michael@walle.cc>
Cc: krzysztof.kozlowski@linaro.org, broonie@kernel.org,
devicetree@vger.kernel.org, jerry.huang@nxp.com,
krzysztof.kozlowski+dt@linaro.org, leoyang.li@nxp.com,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, linux-spi@vger.kernel.org,
shawnguo@kernel.org, Vladimir Oltean <olteanv@gmail.com>
Subject: Re: [EXT] Re: [PATCH 1/2 v4] dt-bindings: dspi: added for semtech sx1301
Date: Thu, 21 Apr 2022 09:23:52 -0500 [thread overview]
Message-ID: <YmFo+EntwxIsco/t@robh.at.kernel.org> (raw)
In-Reply-To: <20220421094421.288672-1-michael@walle.cc>
On Thu, Apr 21, 2022 at 11:44:21AM +0200, Michael Walle wrote:
> On 21/04/2022 11:11, Jerry Huang wrote:
> >> Please also answer Michael's comments.
> >>
> >> [Jerry Huang] I double checked the MikroBus devices, we used two MikcroBus devices:
> >> BLE P click: https://www.mikroe.com/ble-p-click
> >> BEE click: https://www.mikroe.com/bee-click
> >> Both of them are SPI interface connect to ls1028ardb through MiKcroBus interface.
> >> So the name "semtech sx1301" is not correct for this node.
> >
> > I asked to remove the words "Devicetree bindings" and this was not finished.
> >
> > Now you mention that entire name of device is wrong... It's confusing. I
> > don't know what device you are describing here. I expect you know. :)
> >
> > What is this binding about exactly?
>
> I *think* it's just exposing the mikrobus connector as an spidev device.
> There was a former attempt by Vladimir here [1]. Now as it the nature
> of such a connector that you can connect a myriad of devices there, it
> doesn't really make sense to have a just particular one described. What
> happens if that one will switch from spidev to a real driver in the
> kernel? So using "spidev" for the compatible would be the first reflex.
> But as described in the spidev driver this is plain wrong (and also causes
> a warning/info message it) because it should describe the actual hardware.
>
> Thus I proposed to use DT overlays which are loaded according to what
> is actually attached to the header, so a real driver could be loaded.
>
> But there *could* be a sane default which then could be replaced in
> an DT overlay. Like "mirkobus-socket" or similar, which might expose
> spidev. Actually it is more than just SPI, there is GPIO and resets and
> I2C. Maybe it should be an MFD? I don't know. But that is something for
> the DT maintainers to decide if they'll allow such "generic" devices.
generic devices, no. MFD, no.
What's needed here is a connector node (and driver) for the mikrobus
socket. The connector node's purpose is to decouple the host DT from
add-on board overlay DT. Something like this:
connector {
// And a more specific compatible if pins can have alt funcs?
// Spec version needed?
compatible = "mikrobus-socket";
// Will need regulators defined if child devices expect
// regulators
vcc-33-supply = <®33>;
vcc-5-supply = <®5v>;
i2c-parent = <&i2c1>; // Already a defined property
spi-parent = <&spi0>; // New
// RST pin
reset-gpios = <&gpio 4 0>;
// remap 'INT' (index 0) to host interrupt
#interrupt-cells = <2>;
#address-cells = <0>;
interrupt-map = <0 0 &gpio 3 0>;
spi {
//devices
};
i2c {
};
};
The DT spec defines 'foo-map' properties extending interrupt-map.
Currently only GPIO is defined. We might want to do the same thing for
PWM. Or we make the connector node both a PWM consumer and provider.
Rob
next prev parent reply other threads:[~2022-04-21 14:23 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-20 7:31 [PATCH 1/2 v4] dt-bindings: dspi: added for semtech sx1301 Changming Huang
2022-04-20 7:31 ` [PATCH 2/2 v4] arm64: dts: fsl-ls1028a: add dspi2 support Changming Huang
2022-04-20 12:06 ` [PATCH 1/2 v4] dt-bindings: dspi: added for semtech sx1301 Krzysztof Kozlowski
2022-04-21 9:11 ` [EXT] " Jerry Huang
2022-04-21 9:18 ` Krzysztof Kozlowski
2022-04-21 9:35 ` Jerry Huang
2022-04-21 9:44 ` Michael Walle
2022-04-21 10:06 ` Jerry Huang
2022-04-21 11:08 ` Krzysztof Kozlowski
2022-04-21 11:56 ` Michael Walle
2022-04-21 14:23 ` Rob Herring [this message]
2022-04-21 15:16 ` Michael Walle
2022-04-21 19:08 ` Rob Herring
2022-04-22 2:19 ` Jerry Huang
2022-04-21 14:27 ` Rob Herring
2022-04-20 13:29 ` Rob Herring
2022-04-21 9:12 ` [EXT] " Jerry Huang
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