linux-kernel - Re: [PATCH 5/7] drivers:input:ads7846(+tsc2046): add new common binding names, pre-calibration and flipping

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Message-Id: <C2304EBD-A75D-495A-9A90-5E2082E983B7@goldelico.com>
Date:	Mon, 9 Nov 2015 18:36:48 +0100
From:	"H. Nikolaus Schaller" <hns@...delico.com>
To:	Rob Herring <robh@...nel.org>
Cc:	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	Benoît Cousson <bcousson@...libre.com>,
	Tony Lindgren <tony@...mide.com>,
	Russell King <linux@....linux.org.uk>,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-omap@...r.kernel.org, gta04-owner@...delico.com
Subject: Re: [PATCH 5/7] drivers:input:ads7846(+tsc2046): add new common binding names, pre-calibration and flipping


Am 09.11.2015 um 18:31 schrieb Rob Herring <robh@...nel.org>:

> On Fri, Nov 06, 2015 at 04:14:47PM +0100, H. Nikolaus Schaller wrote:
>> commit b98abe52fa8e ("Input: add common DT binding for touchscreens")
>> introduced common DT bindings for touchscreens [1] and a helper function to
>> parse the DT.
>> 
>> This has been integrated and interpretation of the inversion (flipping)
>> properties for the x and y axis has been added to accommodate any
>> orientation of the touch in relation to the LCD.
>> 
>> By scaling the min/max ADC values to the screen size it is now possible to
>> pre-calibrate the touch so that is (almost) exactly matches the LCD it is
>> glued onto. This allows to well enough operate the touch before a user
>> space calibration can improve the precision.
>> 
>> [1]: Documentation/devicetree/bindings/input/touchscreen/touchscreen.txt
>> 
>> Signed-off-by: H. Nikolaus Schaller <hns@...delico.com>
>> ---
>> .../devicetree/bindings/input/ads7846.txt          |  8 ++-
> 
> The binding change looks okay, but...
> 
>> @@ -1213,7 +1259,7 @@ static const struct ads7846_platform_data *ads7846_probe_dt(struct device *dev)
>> 	of_property_read_u16(node, "ti,vref-mv", &pdata->vref_mv);
>> 	pdata->keep_vref_on = of_property_read_bool(node, "ti,keep-vref-on");
>> 
>> -	pdata->swap_xy = of_property_read_bool(node, "ti,swap-xy");
>> +	pdata->swap_xy = of_property_read_bool(node, "touchscreen-swapped-x-y");
> 
> This will break with old dtb's.

We have a patch for all boards in tree (external dtbs must be modified by their maintainers).

> The driver should look for either 
> property.

It is easy to recognize either one.

Noted for V2.

BR and thanks,
Nikolaus--
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