[PATCH 1/3] touchscreen: sun4i-ts: A10 (sun4i) has a different temperature curve

[Hans de Goede]

Hi,

On 08-03-15 22:13, Dmitry Torokhov wrote:
> On Sun, Mar 08, 2015 at 09:53:40PM +0100, Hans de Goede wrote:
>> Testing has revealed that the temperature in the rtp controller of the A10
>> (sun4i) SoC has a different curve then on the A13 (sun5i) and later models.
>>
>> Add a new sun5i-a13-ts compatible to differentiate the newer models and
>> set the curve based on the compatible string.
>>
>> The new curve is still not ideal on all A10-s, that seems to have to
>> do with there being a large spread between different A10-s out there,
>> the new curve us based on callibration results on 4 completely different
>> models:
>>                          raw min raw max temp min temp max stepsize offset
>> Tong Zhang's hackberry    2402    2680    45.0     80.0    0.125   -255.3
>> Hansg's Cubieboard        2207    2300    36.0     45.0    0.096   -175.8
>> Olliver's lime 1 (*):     2258    2537    48.3     87.1    0.139   -265.7
>> Olliver's lime 2 (*):     2222    2486    46.7     91.7    0.170   -331.0
>> *) from: http://linux-sunxi.org/Temperature_Calibration
>>
>> Average all 4:                                             0.133   -257.0
>> Average without outliers (middle 2):                       0.132   -261.0
>>
>> Since it is better to slightly overreport the temperature this patch uses
>> the average of all 4 as curve.
>>
>> This fixes the temperature reported on the A10 being much higher then
>> expected.
>>
>> Cc: Tong Zhang <lovewilliam at gmail.com>
>> Cc: Olliver Schinagl <o.schinagl at ultimaker.com>
>> Reported-by: Tong Zhang <lovewilliam at gmail.com>
>> Signed-off-by: Hans de Goede <hdegoede at redhat.com>
>
>
> Applied, thank you.

Thanks.

Note I've just found out that I've made a math error, the offset as I've used it is
in degrees, but the actual code applies the offset before multiplying by stepsize :|

Given that this is rather backwards (every math course ever thought applies
the multiplication before the offset for linear functions. I'll do a follow up
patch fixing the code to do the logical thing, and adjusting the offset for
the other models accordingly.

Regards,

Hans



>
>> ---
>>   .../devicetree/bindings/input/touchscreen/sun4i.txt      |  3 ++-
>>   drivers/input/touchscreen/sun4i-ts.c                     | 16 +++++++++++++---
>>   2 files changed, 15 insertions(+), 4 deletions(-)
>>
>> diff --git a/Documentation/devicetree/bindings/input/touchscreen/sun4i.txt b/Documentation/devicetree/bindings/input/touchscreen/sun4i.txt
>> index 433332d..d59d252 100644
>> --- a/Documentation/devicetree/bindings/input/touchscreen/sun4i.txt
>> +++ b/Documentation/devicetree/bindings/input/touchscreen/sun4i.txt
>> @@ -2,7 +2,8 @@ sun4i resistive touchscreen controller
>>   --------------------------------------
>>
>>   Required properties:
>> - - compatible: "allwinner,sun4i-a10-ts" or "allwinner,sun6i-a31-ts"
>> + - compatible: "allwinner,sun4i-a10-ts", "allwinner,sun5i-a13-ts" or
>> +   "allwinner,sun6i-a31-ts"
>>    - reg: mmio address range of the chip
>>    - interrupts: interrupt to which the chip is connected
>>    - #thermal-sensor-cells: shall be 0
>> diff --git a/drivers/input/touchscreen/sun4i-ts.c b/drivers/input/touchscreen/sun4i-ts.c
>> index b93a28b..66ccd5a 100644
>> --- a/drivers/input/touchscreen/sun4i-ts.c
>> +++ b/drivers/input/touchscreen/sun4i-ts.c
>> @@ -258,6 +258,15 @@ static int sun4i_ts_probe(struct platform_device *pdev)
>>   		/* Allwinner SDK has temperature = -271 + (value / 6) (C) */
>>   		ts->temp_offset = 1626;
>>   		ts->temp_step = 167;
>> +	} else if (of_device_is_compatible(np, "allwinner,sun4i-a10-ts")) {
>> +		/*
>> +		 * The A10 temperature sensor has quite a wide spread, these
>> +		 * parameters are based on the averaging of the calibration
>> +		 * results of 4 completely different boards, with a spread of
>> +		 * temp_step from 96 - 170 and temp_offset from 1758 - 3310.
>> +		 */
>> +		ts->temp_offset = 2570;
>> +		ts->temp_step = 133;
>>   	} else {
>>   		/*
>>   		 * The user manuals do not contain the formula for calculating
>> @@ -330,10 +339,10 @@ static int sun4i_ts_probe(struct platform_device *pdev)
>>   	 * finally enable tp mode.
>>   	 */
>>   	reg = STYLUS_UP_DEBOUN(5) | STYLUS_UP_DEBOUN_EN(1);
>> -	if (of_device_is_compatible(np, "allwinner,sun4i-a10-ts"))
>> -		reg |= TP_MODE_EN(1);
>> -	else
>> +	if (of_device_is_compatible(np, "allwinner,sun6i-a31-ts"))
>>   		reg |= SUN6I_TP_MODE_EN(1);
>> +	else
>> +		reg |= TP_MODE_EN(1);
>>   	writel(reg, ts->base + TP_CTRL1);
>>
>>   	/*
>> @@ -383,6 +392,7 @@ static int sun4i_ts_remove(struct platform_device *pdev)
>>
>>   static const struct of_device_id sun4i_ts_of_match[] = {
>>   	{ .compatible = "allwinner,sun4i-a10-ts", },
>> +	{ .compatible = "allwinner,sun5i-a13-ts", },
>>   	{ .compatible = "allwinner,sun6i-a31-ts", },
>>   	{ /* sentinel */ }
>>   };
>> --
>> 2.3.1
>>
>