linux-kernel - Re: [PATCH 1/3] input: touchscreen: ar1021

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Date:   Thu, 13 Apr 2017 08:38:39 +0200
From:   Martin Kepplinger <martin.kepplinger@...zinger.com>
To:     Dmitry Torokhov <dmitry.torokhov@...il.com>
CC:     <christian.gmeiner@...il.com>, <linux@...ck-us.net>,
        <linux-input@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <devicetree@...r.kernel.org>
Subject: Re: [PATCH 1/3] input: touchscreen: ar1021_i2c: add support for
 AR1020



On 2017-04-12 17:40, Dmitry Torokhov wrote:
> Hi Martin,
> 
> On Tue, Apr 11, 2017 at 12:27:57PM +0200, Martin Kepplinger wrote:
>> ar1021_i2c simply also supports the ar1020 device we use. This is tested.
>> They also share the same datasheet:
>>
>>    http://ww1.microchip.com/downloads/en/DeviceDoc/40001393C.pdf
>>
>> We differentiate not only to make it obvious that we support both devices,
>> but also to be able to implement the few model specific things in the
>> future.
>>
>> Signed-off-by: Martin Kepplinger <martin.kepplinger@...zinger.com>
>> ---
>>  drivers/input/touchscreen/Kconfig      |  4 ++--
>>  drivers/input/touchscreen/ar1021_i2c.c | 13 ++++++++++---
>>  2 files changed, 12 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/input/touchscreen/Kconfig b/drivers/input/touchscreen/Kconfig
>> index 33c62e5..535b91a 100644
>> --- a/drivers/input/touchscreen/Kconfig
>> +++ b/drivers/input/touchscreen/Kconfig
>> @@ -96,8 +96,8 @@ config TOUCHSCREEN_AR1021_I2C
>>  	tristate "Microchip AR1021 i2c touchscreen"
>>  	depends on I2C && OF
>>  	help
>> -	  Say Y here if you have the Microchip AR1021 touchscreen controller
>> -	  chip in your system.
>> +	  Say Y here if you have the Microchip AR1020 or AR1021 touchscreen
>> +	  controller chip in your system.
>>  
>>  	  If unsure, say N.
>>  
>> diff --git a/drivers/input/touchscreen/ar1021_i2c.c b/drivers/input/touchscreen/ar1021_i2c.c
>> index 6562b17..1767257 100644
>> --- a/drivers/input/touchscreen/ar1021_i2c.c
>> +++ b/drivers/input/touchscreen/ar1021_i2c.c
>> @@ -1,5 +1,5 @@
>>  /*
>> - * Microchip AR1021 driver for I2C
>> + * Microchip AR1020 and AR1021 driver for I2C
>>   *
>>   * Author: Christian Gmeiner <christian.gmeiner@...il.com>
>>   *
>> @@ -24,6 +24,11 @@ struct ar1021_i2c {
>>  	u8 data[AR1021_TOCUH_PKG_SIZE];
>>  };
>>  
>> +enum {
>> +	ar1021,
>> +	ar1020,
>> +};
>> +
>>  static irqreturn_t ar1021_i2c_irq(int irq, void *dev_id)
>>  {
>>  	struct ar1021_i2c *ar1021 = dev_id;
>> @@ -151,13 +156,15 @@ static int __maybe_unused ar1021_i2c_resume(struct device *dev)
>>  static SIMPLE_DEV_PM_OPS(ar1021_i2c_pm, ar1021_i2c_suspend, ar1021_i2c_resume);
>>  
>>  static const struct i2c_device_id ar1021_i2c_id[] = {
>> -	{ "MICROCHIP_AR1021_I2C", 0 },
>> +	{ "MICROCHIP_AR1021_I2C", ar1021 },
>> +	{ "MICROCHIP_AR1020_I2C", ar1020 },
>>  	{ },
>>  };
>>  MODULE_DEVICE_TABLE(i2c, ar1021_i2c_id);
>>  
>>  static const struct of_device_id ar1021_i2c_of_match[] = {
>>  	{ .compatible = "microchip,ar1021-i2c", },
>> +	{ .compatible = "microchip,ar1020-i2c", },
>>  	{ }
>>  };
>>  MODULE_DEVICE_TABLE(of, ar1021_i2c_of_match);
>> @@ -175,5 +182,5 @@ static struct i2c_driver ar1021_i2c_driver = {
>>  module_i2c_driver(ar1021_i2c_driver);
>>  
>>  MODULE_AUTHOR("Christian Gmeiner <christian.gmeiner@...il.com>");
>> -MODULE_DESCRIPTION("Microchip AR1021 I2C Driver");
>> +MODULE_DESCRIPTION("Microchip AR1020 and AR1021 I2C Driver");
>>  MODULE_LICENSE("GPL");
>> -- 
>> 2.1.4
>>
> 
> I do not see where you handle ar1020 differently from ar1021. If devices
> are compatible, you do not need to add a new compatible to the driver,
> simply use it in the binding:
> 
> 	compatible = "microchip,ar1020-i2c", "microchip,ar1021-i2c";
> 
> Thanks.
> 

Why would you use "microchip,ar1020-i2c" in the dts if it's not
available? people don't obviously see, by grepping or reading,
that they have a compatible driver. ... or did I get you wrong?

I don't handle anything differently now. Factory reset has to be done
differntly though, as one example. So it'd be nice to have the option
to add data.

thanks
                          martin