RE: [PATCH v2 2/5] Documentation: Detail permitted DT properties for the imx6ul_tsc

From: Chen Bough
Date: Fri Aug 21 2015 - 04:30:30 EST


Hi Markus,

> -----Original Message-----
> From: Markus Pargmann [mailto:mpa@xxxxxxxxxxxxxx]
> Sent: Wednesday, August 19, 2015 1:55 PM
> To: Chen Haibo-B51421
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> 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@xxxxxxxxxxxxx>
> > ---
> > .../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@02040000 {
> > + 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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