linux-kernel - Re: [PATCH] ARM: dts: Provide support for reading ID code from MVB device (BK4)

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Date:   Mon, 3 Dec 2018 10:33:33 +0100
From:   Lukasz Majewski <lukma@...x.de>
To:     Shawn Guo <shawnguo@...nel.org>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        Stefan Agner <stefan@...er.ch>,
        Fabio Estevam <festevam@...il.com>,
        Fabio Estevam <fabio.estevam@....com>
Subject: Re: [PATCH] ARM: dts: Provide support for reading ID code from MVB
 device (BK4)

Hi Shawn,

Thank you for the review.

> On Tue, Nov 13, 2018 at 01:12:13PM +0100, Lukasz Majewski wrote:
> > The procedure to read this ID value is as follows:
> > 
> > rmmod spi_fsl_dspi
> > insmod spi-gpio.ko
> > 
> > echo 504 > /sys/class/gpio/export
> > cat /sys/class/gpio/gpio504/value
> > ...
> > echo 511 > /sys/class/gpio/export
> > cat /sys/class/gpio/gpio511/value
> > 
> > rmmod spi-gpio.ko
> > insmod spi_fsl_dspi
> > 
> > Signed-off-by: Lukasz Majewski <lukma@...x.de>
> 
> A prefix like 'ARM: dts: vf610-bk4: ...' might be better.

Ok.

> 
> > ---
> >  arch/arm/boot/dts/vf610-bk4.dts | 31
> > +++++++++++++++++++++++++++++++ 1 file changed, 31 insertions(+)
> > 
> > diff --git a/arch/arm/boot/dts/vf610-bk4.dts
> > b/arch/arm/boot/dts/vf610-bk4.dts index cab95714c058..f01c735807ae
> > 100644 --- a/arch/arm/boot/dts/vf610-bk4.dts
> > +++ b/arch/arm/boot/dts/vf610-bk4.dts
> > @@ -59,6 +59,29 @@
> >  		regulator-min-microvolt = <3300000>;
> >  		regulator-max-microvolt = <3300000>;
> >  	};
> > +
> > +	spi_gpio {
> 
> We recommend hyphen rather than underscore be used in node name.

Ok. I will change it to spi-gpio

> 
> > +		compatible = "spi-gpio";
> > +		pinctrl-0 = <&pinctrl_gpio_spi>;
> > +		pinctrl-names = "default";
> > +		#address-cells = <1>;
> > +		#size-cells = <0>;
> > +		/* PTD12 ->RPIO[91] */
> > +		sck-gpios  = <&gpio2 27 GPIO_ACTIVE_LOW>;
> > +		/* PTD10 ->RPIO[89] */
> > +		miso-gpios = <&gpio2 25 GPIO_ACTIVE_HIGH>;
> > +		num-chipselects = <0>;
> > +
> > +		72xx165@0 {
> 
> Please use a generic name for the node.

This is a bit tricky.

Other DTS definitions for this compatible:

sn65hvs882: sn65hvs882@0 {
	compatible = "pisosr-gpio";
	...
	}

They use the exact used IC name - sn65hvs882, which IMHO is the way how
this node shall be described.

The reason is that the compatible is "pisosr-gpio" -> parallel input
serial output shift regsiter - gpio.

By adding the exact name of connected electronic IC - sn65hvs882 and in
my case IC from the 72xx165 family provides good description of the HW.

Maybe you have other idea how to provide the name of the IC connected?

> 
> Shawn
> 
> > +			compatible = "pisosr-gpio";
> > +			reg = <0>;
> > +			gpio-controller;
> > +			#gpio-cells = <2>;
> > +			/* PTB18 -> RGPIO[40] */
> > +			load-gpios  = <&gpio1 8 GPIO_ACTIVE_LOW>;
> > +			spi-max-frequency = <100000>;
> > +		};
> > +	};
> >  };
> >  
> >  &adc0 {
> > @@ -430,6 +453,14 @@
> >  		>;
> >  	};
> >  
> > +	pinctrl_gpio_spi: pinctrl-gpio-spi {
> > +		fsl,pins = <
> > +			VF610_PAD_PTB18__GPIO_40        0x1183
> > +			VF610_PAD_PTD10__GPIO_89        0x1183
> > +			VF610_PAD_PTD12__GPIO_91        0x1183
> > +		>;
> > +	};
> > +
> >  	pinctrl_i2c2: i2c2grp {
> >  		fsl,pins = <
> >  			VF610_PAD_PTA22__I2C2_SCL
> > 0x34df -- 
> > 2.11.0
> > 




Best regards,

Lukasz Majewski

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