linux-kernel - Re: [PATCH v2 3/3] input: touchscreen mc13xxx: Add mc34708 support

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Date:   Mon, 15 Jul 2019 11:13:38 +0200
From:   Lukasz Majewski <lukma@...x.de>
To:     Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc:     Lee Jones <lee.jones@...aro.org>, linux-kernel@...r.kernel.org,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Enrico Weigelt <info@...ux.net>,
        Thomas Gleixner <tglx@...utronix.de>,
        Kate Stewart <kstewart@...uxfoundation.org>,
        linux-input@...r.kernel.org
Subject: Re: [PATCH v2 3/3] input: touchscreen mc13xxx: Add mc34708 support

Hi Dmitry,

> Hi Lukasz,
>  
> On Fri, Jul 12, 2019 at 12:23:46AM +0200, Lukasz Majewski wrote:
> > From: Sascha Hauer <s.hauer@...gutronix.de>
> > 
> > The mc34708 has a different bit to enable pen detection. This
> > adds the driver data and devtype necessary to probe the device
> > and to distinguish between the mc13783 and the mc34708.
> > 
> > Signed-off-by: Sascha Hauer <s.hauer@...gutronix.de>
> > Signed-off-by: Lukasz Majewski <lukma@...x.de>
> > 
> > ---
> > Changes for v2:
> > - Change nested if statements to a single one (with cr0 > ...)
> > - Replace hardcoded max resistance value (4080) with a generic
> > driver data value.
> > - Introduce new include/linux/mfd/mc34708.h header file for mc34708
> > specific defines
> > - Define as driver data mask and value for accessing mc13xxx
> > registers
> > 
> > Changes from the original patch:
> > - Simplify the mcXXXXX_set_pen_detection functions
> > - Fix checkpatch warnings
> > ---
> >  drivers/input/touchscreen/mc13783_ts.c | 59
> > +++++++++++++++++++++++++++++++--- 1 file changed, 55
> > insertions(+), 4 deletions(-)
> > 
> > diff --git a/drivers/input/touchscreen/mc13783_ts.c
> > b/drivers/input/touchscreen/mc13783_ts.c index
> > edd49e44e0c9..8fd3d0e47f57 100644 ---
> > a/drivers/input/touchscreen/mc13783_ts.c +++
> > b/drivers/input/touchscreen/mc13783_ts.c @@ -10,6 +10,7 @@
> >   */
> >  #include <linux/platform_device.h>
> >  #include <linux/mfd/mc13783.h>
> > +#include <linux/mfd/mc34708.h>
> >  #include <linux/kernel.h>
> >  #include <linux/module.h>
> >  #include <linux/input.h>
> > @@ -30,6 +31,8 @@ MODULE_PARM_DESC(sample_tolerance,
> >  		"is supposed to be wrong and is discarded.  Set to
> > 0 to " "disable this check.");
> >  
> > +struct mc13xxx_driver_data;  
> 
> Why don't you define the structure here instead of sing forward
> declaration? 

I will define the structure here.

> The structure is also commonly called as xxx_chip, so
> struct mc13xxx_chip {
> 	...
> };

Ok.

> 
> > +
> >  struct mc13783_ts_priv {
> >  	struct input_dev *idev;
> >  	struct mc13xxx *mc13xxx;
> > @@ -37,6 +40,33 @@ struct mc13783_ts_priv {
> >  	unsigned int sample[4];
> >  	u8 ato;
> >  	bool atox;
> > +	struct mc13xxx_driver_data *drvdata;  
> 
> const struct mc13xxx_chip *chip;

Ok. I will adjust the name.

> 
> > +};
> > +
> > +enum mc13xxx_type {
> > +	MC13XXX_TYPE_MC13783,
> > +	MC13XXX_TYPE_MC34708,
> > +};
> > +
> > +struct mc13xxx_driver_data {
> > +	enum mc13xxx_type type;
> > +	int max_resistance;
> > +	u32 reg_mask;
> > +	u32 reg_value;
> > +};
> > +
> > +static struct mc13xxx_driver_data mc13783_driver_data = {
> > +	.type = MC13XXX_TYPE_MC13783,
> > 	.max_resistance = 4096,
> > +	.reg_mask = MC13XXX_ADC0_TSMOD_MASK,
> > +	.reg_value = MC13XXX_ADC0_TSMOD0,
> > +};
> > +
> > +static struct mc13xxx_driver_data mc34708_driver_data = {
> > +	.type = MC13XXX_TYPE_MC34708,
> > +	.max_resistance = 4080,
> > +	.reg_mask = MC34708_ADC0_TSMASK,
> > +	.reg_value = MC34708_ADC0_TSPENDETEN,
> >  };  
> 
> Have these 2 closer to the ID table.

I will move those two instances of struct mc13xxx_chip closer to the ID
table.

> 
> >  
> >  static irqreturn_t mc13783_ts_handler(int irq, void *data)
> > @@ -93,6 +123,10 @@ static void mc13783_ts_report_sample(struct
> > mc13783_ts_priv *priv) 
> >  	cr0 = (cr0 + cr1) / 2;
> >  
> > +	if (priv->drvdata->type == MC13XXX_TYPE_MC34708 &&
> > +	    cr0 > priv->drvdata->max_resistance)
> > +		cr0 = 0;  
> 
> I would like to avoid the type comparisons. Given that both cr0 and
> cr1 can't be more than 4095 (because we limit them when parsing
> sampling data) I think we can simply say
> 
> 	if (cr0 > priv->chip->max_resistance)
> 		cr0 = 0;

Ok.

> 
> Thanks.
> 




Best regards,

Lukasz Majewski

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