Re: [PATCH 5/5] Input: ads7846: set proper debounce time in driver level

Re: [PATCH 5/5] Input: ads7846: set proper debounce time in driver level

[Igor Grinberg]

Hi,

This is input subsystem, add Dmitry and linux-input.

On 06/11/12 17:00, Zumeng Chen wrote:
> If we don't set proper debouce time for ads7846, then there are
> flooded interrupt counters of ads7846 responding to one time
> touch on screen, so the driver couldn't work well.
> 
> And since most OMAP3 series boards pass NULL pointer of board_pdata
> to omap_ads7846_init, so it's more proper to set it in driver level
> after having gpio_request done.

What about other non-OMAP platforms?

NULL pointer for board_pdata, only means that the default pdata is used.
Please, see the common-board-devices.c file more closely.

> 
> This patch has been validated on 3530evm.
> 
> Signed-off-by: Zumeng Chen <zumeng.chen@gmail.com>
> Signed-off-by: Syed Mohammed Khasim <khasim@ti.com>
> Signed-off-by: Tony Lindgren <tony@atomide.com>
> ---
>  drivers/input/touchscreen/ads7846.c |    2 ++
>  1 files changed, 2 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/input/touchscreen/ads7846.c b/drivers/input/touchscreen/ads7846.c
> index f02028e..a82a5fb 100644
> --- a/drivers/input/touchscreen/ads7846.c
> +++ b/drivers/input/touchscreen/ads7846.c
> @@ -61,6 +61,7 @@
>  
>  /* this driver doesn't aim at the peak continuous sample rate */
>  #define	SAMPLE_BITS	(8 /*cmd*/ + 16 /*sample*/ + 2 /* before, after */)
> +#define	DEBOUNCE_TIME	310 /* About 10 ms */

I think hard coding this value is wrong.
Can't it be derived from the pdata->debounce_* fields?

>  
>  struct ts_event {
>  	/*
> @@ -980,6 +981,7 @@ static int __devinit ads7846_setup_pendown(struct spi_device *spi, struct ads784
>  		}
>  
>  		ts->gpio_pendown = pdata->gpio_pendown;
> +		gpio_set_debounce(pdata->gpio_pendown, DEBOUNCE_TIME);
>  
>  	} else {
>  		dev_err(&spi->dev, "no get_pendown_state nor gpio_pendown?\n");

-- 
Regards,
Igor.

Re: [PATCH 5/5] Input: ads7846: set proper debounce time in driver level

[Zumeng Chen]

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2012/6/11 Igor Grinberg <grinberg@compulab.co.il>

> Hi,
>
> This is input subsystem, add Dmitry and linux-input.
>
> On 06/11/12 17:00, Zumeng Chen wrote:
> > If we don't set proper debouce time for ads7846, then there are
> > flooded interrupt counters of ads7846 responding to one time
> > touch on screen, so the driver couldn't work well.
> >
> > And since most OMAP3 series boards pass NULL pointer of board_pdata
> > to omap_ads7846_init, so it's more proper to set it in driver level
> > after having gpio_request done.
>
> What about other non-OMAP platforms?
>
Good point, I thought it should be the same situation, and I have no other
boards
to validate it :) Then I'll fall back on my original patch to bracket them
with OMAP3EVM

>
> NULL pointer for board_pdata, only means that the default pdata is used.
> Please, see the common-board-devices.c file more closely.
>
Yes,  I just went through again, two points:

1 )  get_pendown_state is not set for OMAP3 boards, and the state
      will be get by gpio_get_value(gpio-omap.c)
      The second path will be available in the ads7846_setup_pendown
      if (pdata->get_pendown_state) {
                ts->get_pendown_state = pdata->get_pendown_state;
      } else if (gpio_is_valid(pdata->gpio_pendown)) {

2 )  All omap3 boards set gpio_pendown for pdata.
      So it had better we set_debounce in driver level after
gpio_request_one
      having done
      I'll remove DEBOUNCE_TIME in V2 and change into like following:

+#ifdef CONFIG_MACH_OMAP3EVM
+               /* 310 means 10 microsecond for omap3 */
+               gpio_set_debounce(pdata->gpio_pendown, 310);
+#endif


> >
> > This patch has been validated on 3530evm.
> >
> > Signed-off-by: Zumeng Chen <zumeng.chen@gmail.com>
> > Signed-off-by: Syed Mohammed Khasim <khasim@ti.com>
> > Signed-off-by: Tony Lindgren <tony@atomide.com>
> > ---
> >  drivers/input/touchscreen/ads7846.c |    2 ++
> >  1 files changed, 2 insertions(+), 0 deletions(-)
> >
> > diff --git a/drivers/input/touchscreen/ads7846.c
> b/drivers/input/touchscreen/ads7846.c
> > index f02028e..a82a5fb 100644
> > --- a/drivers/input/touchscreen/ads7846.c
> > +++ b/drivers/input/touchscreen/ads7846.c
> > @@ -61,6 +61,7 @@
> >
> >  /* this driver doesn't aim at the peak continuous sample rate */
> >  #define      SAMPLE_BITS     (8 /*cmd*/ + 16 /*sample*/ + 2 /* before,
> after */)
> > +#define      DEBOUNCE_TIME   310 /* About 10 ms */
>
> I think hard coding this value is wrong.
>
Yes, me too.

> Can't it be derived from the pdata->debounce_* fields?
>
Yes, I agreed this way, and to be honest, my first choice
is to find if there is a member for debounce, but no. And
there is no more sense to derive it from debounce_max,
although which is the right value for us.

So I have to use the hardcode here.

Regards,
Zumeng


> >
> >  struct ts_event {
> >       /*
> > @@ -980,6 +981,7 @@ static int __devinit ads7846_setup_pendown(struct
> spi_device *spi, struct ads784
> >               }
> >
> >               ts->gpio_pendown = pdata->gpio_pendown;
> > +             gpio_set_debounce(pdata->gpio_pendown, DEBOUNCE_TIME);
> >
> >       } else {
> >               dev_err(&spi->dev, "no get_pendown_state nor
> gpio_pendown?\n");
>
> --
> Regards,
> Igor.
>

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Re: [PATCH 5/5] Input: ads7846: set proper debounce time in driver level

[Igor Grinberg]

On 06/12/12 05:49, Zumeng Chen wrote:
> 
> 
> 2012/6/11 Igor Grinberg <grinberg@compulab.co.il <mailto:grinberg@compulab.co.il>>
> 
>     Hi,
> 
>     This is input subsystem, add Dmitry and linux-input.
> 
>     On 06/11/12 17:00, Zumeng Chen wrote:
>     > If we don't set proper debouce time for ads7846, then there are
>     > flooded interrupt counters of ads7846 responding to one time
>     > touch on screen, so the driver couldn't work well.
>     >
>     > And since most OMAP3 series boards pass NULL pointer of board_pdata
>     > to omap_ads7846_init, so it's more proper to set it in driver level
>     > after having gpio_request done.
> 
>     What about other non-OMAP platforms?
> 
> Good point, I thought it should be the same situation, and I have no other boards
> to validate it :) Then I'll fall back on my original patch to bracket them with OMAP3EVM

This isn't a good solution either...

> 
> 
>     NULL pointer for board_pdata, only means that the default pdata is used.
>     Please, see the common-board-devices.c file more closely.
> 
> Yes,  I just went through again, two points:
> 
> 1 )  get_pendown_state is not set for OMAP3 boards, and the state

You can supply your own pdata and provide the get_pendown_state() callback.

>       will be get by gpio_get_value(gpio-omap.c)
>       The second path will be available in the ads7846_setup_pendown
>       if (pdata->get_pendown_state) {
>                 ts->get_pendown_state = pdata->get_pendown_state;
>       } else if (gpio_is_valid(pdata->gpio_pendown)) {
> 
> 2 )  All omap3 boards set gpio_pendown for pdata.
>       So it had better we set_debounce in driver level after gpio_request_one
>       having done
>       I'll remove DEBOUNCE_TIME in V2 and change into like following:
> 
> +#ifdef CONFIG_MACH_OMAP3EVM
> +               /* 310 means 10 microsecond for omap3 */
> +               gpio_set_debounce(pdata->gpio_pendown, 310);
> +#endif

I don't think this kind of fix is acceptable...

> 
> 
>     >
>     > This patch has been validated on 3530evm.
>     >
>     > Signed-off-by: Zumeng Chen <zumeng.chen@gmail.com <mailto:zumeng.chen@gmail.com>>
>     > Signed-off-by: Syed Mohammed Khasim <khasim@ti.com <mailto:khasim@ti.com>>
>     > Signed-off-by: Tony Lindgren <tony@atomide.com <mailto:tony@atomide.com>>
>     > ---
>     >  drivers/input/touchscreen/ads7846.c |    2 ++
>     >  1 files changed, 2 insertions(+), 0 deletions(-)
>     >
>     > diff --git a/drivers/input/touchscreen/ads7846.c b/drivers/input/touchscreen/ads7846.c
>     > index f02028e..a82a5fb 100644
>     > --- a/drivers/input/touchscreen/ads7846.c
>     > +++ b/drivers/input/touchscreen/ads7846.c
>     > @@ -61,6 +61,7 @@
>     >
>     >  /* this driver doesn't aim at the peak continuous sample rate */
>     >  #define      SAMPLE_BITS     (8 /*cmd*/ + 16 /*sample*/ + 2 /* before, after */)
>     > +#define      DEBOUNCE_TIME   310 /* About 10 ms */
> 
>     I think hard coding this value is wrong.
> 
> Yes, me too.
> 
>     Can't it be derived from the pdata->debounce_* fields?
> 
> Yes, I agreed this way, and to be honest, my first choice
> is to find if there is a member for debounce, but no. And
> there is no more sense to derive it from debounce_max,
> although which is the right value for us.

It makes sense to me... Why do you think there is no sense?


-- 
Regards,
Igor.