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

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Message-ID: <BY1PR03MB1388BBEF576297D76E7E3F839A650@BY1PR03MB1388.namprd03.prod.outlook.com>
Date:	Fri, 21 Aug 2015 08:30:16 +0000
From:	Chen Bough <Haibo.Chen@...escale.com>
To:	Markus Pargmann <mpa@...gutronix.de>
CC:	"robh+dt@...nel.org" <robh+dt@...nel.org>,
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Subject: RE: [PATCH v2 2/5] Documentation: Detail permitted DT properties for
 the imx6ul_tsc

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. 

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
> >
> >
> >
> 
> --
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