linux-kernel - Re: [PATCH v2 2/5] Documentation: Detail permitted DT properties for the imx6ul

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Date:	Fri, 21 Aug 2015 11:27:25 +0200
From:	Markus Pargmann <mpa@...gutronix.de>
To:	Chen Bough <Haibo.Chen@...escale.com>
Cc:	"robh+dt@...nel.org" <robh+dt@...nel.org>,
	"pawel.moll@....com" <pawel.moll@....com>,
	"mark.rutland@....com" <mark.rutland@....com>,
	"ijc+devicetree@...lion.org.uk" <ijc+devicetree@...lion.org.uk>,
	"galak@...eaurora.org" <galak@...eaurora.org>,
	"shawnguo@...nel.org" <shawnguo@...nel.org>,
	"kernel@...gutronix.de" <kernel@...gutronix.de>,
	"linux@....linux.org.uk" <linux@....linux.org.uk>,
	"dmitry.torokhov@...il.com" <dmitry.torokhov@...il.com>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"sbranden@...adcom.com" <sbranden@...adcom.com>,
	"arnd@...db.de" <arnd@...db.de>,
	"mchehab@....samsung.com" <mchehab@....samsung.com>,
	"christian.gmeiner@...il.com" <christian.gmeiner@...il.com>,
	"scott.liu@....com.tw" <scott.liu@....com.tw>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"hdegoede@...hat.com" <hdegoede@...hat.com>,
	"jonathar@...adcom.com" <jonathar@...adcom.com>,
	"benjamin.tissoires@...hat.com" <benjamin.tissoires@...hat.com>,
	"hans.verkuil@...co.com" <hans.verkuil@...co.com>,
	"hadess@...ess.net" <hadess@...ess.net>,
	"linux-input@...r.kernel.org" <linux-input@...r.kernel.org>,
	"geert@...ux-m68k.org" <geert@...ux-m68k.org>,
	"sebastien.szymanski@...adeus.com" <sebastien.szymanski@...adeus.com>,
	"mamlinav@...il.com" <mamlinav@...il.com>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v2 2/5] Documentation: Detail permitted DT properties for
 the imx6ul_tsc

On Fri, Aug 21, 2015 at 08:30:16AM +0000, Chen Bough wrote:
> Hi Markus,
> 
> > -----Original Message-----
> > From: Markus Pargmann [mailto:mpa@...gutronix.de]
> > Sent: Wednesday, August 19, 2015 1:55 PM
> > To: Chen Haibo-B51421
> > Cc: robh+dt@...nel.org; pawel.moll@....com; mark.rutland@....com;
> > ijc+devicetree@...lion.org.uk; galak@...eaurora.org; shawnguo@...nel.org;
> > kernel@...gutronix.de; linux@....linux.org.uk; dmitry.torokhov@...il.com;
> > devicetree@...r.kernel.org; sbranden@...adcom.com; arnd@...db.de;
> > mchehab@....samsung.com; christian.gmeiner@...il.com;
> > scott.liu@....com.tw; linux-kernel@...r.kernel.org; hdegoede@...hat.com;
> > jonathar@...adcom.com; benjamin.tissoires@...hat.com;
> > hans.verkuil@...co.com; hadess@...ess.net; linux-input@...r.kernel.org;
> > geert@...ux-m68k.org; sebastien.szymanski@...adeus.com;
> > mamlinav@...il.com; linux-arm-kernel@...ts.infradead.org
> > Subject: Re: [PATCH v2 2/5] Documentation: Detail permitted DT properties
> > for the imx6ul_tsc
> > 
> > Hi,
> > 
> > On Tue, Jul 28, 2015 at 05:58:38PM +0800, Haibo Chen wrote:
> > > Here we apply required documentation for the imx6ul touch screen
> > > controller driver which describe available properties and how to use
> > > them.
> > >
> > > Signed-off-by: Haibo Chen <haibo.chen@...escale.com>
> > > ---
> > >  .../bindings/input/touchscreen/imx6ul_tsc.txt      | 36
> > ++++++++++++++++++++++
> > >  1 file changed, 36 insertions(+)
> > >  create mode 100644
> > > Documentation/devicetree/bindings/input/touchscreen/imx6ul_tsc.txt
> > >
> > > diff --git
> > > a/Documentation/devicetree/bindings/input/touchscreen/imx6ul_tsc.txt
> > > b/Documentation/devicetree/bindings/input/touchscreen/imx6ul_tsc.txt
> > > new file mode 100644
> > > index 0000000..ac41c32
> > > --- /dev/null
> > > +++ b/Documentation/devicetree/bindings/input/touchscreen/imx6ul_tsc.t
> > > +++ xt
> > > @@ -0,0 +1,36 @@
> > > +* Freescale i.MX6UL Touch Controller
> > > +
> > > +Required properties:
> > > +- compatible: must be "fsl,imx6ul-tsc".
> > > +- reg: this touch controller address and the ADC2 address.
> > 
> > This suggests that this driver is using a unit ADC2. Which also means
> > that there are more than one ADC which are probably identical?
> > 
> > Shouldn't these ADCs be properly described by their own device nodes
> > instead of these two register ranges, two interrupts and two clocks?
> > 
> > Is 'ADC2' usable without tsc? Then ADC1/ADC2 should perhaps get a proper
> > IIO driver.
> 
> For i.MX6UL, there are two ADC. ADC1 is a normal ADC, and ADC2 can only works for
> TSC, the channels of ADC2 are connected to TSC directly. TSC and ADC2 should work
> together as a touch screen controller. 

But as I understand these are two different units. Wouldn't it be better
to abstract it that way in the DT?

Best regards,

Markus

> 
> For ADC1, it share the driver vf610_adc.c (drivers/iio/adc/vf610_adc.c). 
> 
> Best Regards
> 
> Haibo 
>  
> > 
> > Unfortunately I don't have the reference manual to have a look how this
> > all works.
> > 
> > Best regards,
> > 
> > Markus
> > 
> > > +- interrupts: the interrupt of this touch controller and ADC2.
> > > +- clocks: the root clock of touch controller and ADC2.
> > > +- clock-names; must be "tsc" and "adc".
> > > +- xnur-gpio: the X- gpio this controller connect to.
> > > +  This xnur-gpio returns to high once the finger leave the touch
> > > +screen (The
> > > +  last touch event the touch controller capture).
> > > +
> > > +Optional properties:
> > > +- measure-delay-time: the value of measure delay time.
> > > +  Before X-axis or Y-axis measurement, the screen need some time
> > > +before
> > > +  even potential distribution ready.
> > > +  This value depends on the touch screen.
> > > +- pre-charge-time: the touch screen need some time to precharge.
> > > +  This value depends on the touch screen.
> > > +
> > > +Example:
> > > +	tsc: tsc@...40000 {
> > > +		compatible = "fsl,imx6ul-tsc";
> > > +		reg = <0x02040000 0x4000>, <0x0219c000 0x4000>;
> > > +		interrupts = <GIC_SPI 3 IRQ_TYPE_LEVEL_HIGH>,
> > > +			     <GIC_SPI 101 IRQ_TYPE_LEVEL_HIGH>;
> > > +		clocks = <&clks IMX6UL_CLK_IPG>,
> > > +			 <&clks IMX6UL_CLK_ADC2>;
> > > +		clock-names = "tsc", "adc";
> > > +		pinctrl-names = "default";
> > > +		pinctrl-0 = <&pinctrl_tsc>;
> > > +		xnur-gpio = <&gpio1 3 GPIO_ACTIVE_HIGH>;
> > > +		measure-delay-time = <0xfff>;
> > > +		pre-charge-time = <0xffff>;
> > > +		status = "okay";
> > > +	};
> > > --
> > > 1.9.1
> > >
> > >
> > >
> > 
> > --
> > Pengutronix e.K.                           |
> > |
> > Industrial Linux Solutions                 | http://www.pengutronix.de/
> > |
> > Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0
> > |
> > Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555
> > |

-- 
Pengutronix e.K.                           |                             |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |
Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0    |
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