Re: Please revert 3eea8b5d68c801fec788b411582b803463834752 as it breaks touchscreen on n900.

Maxime Ripard
2015-06-01T21:25:09Z

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Hi Dmitry,

On Mon, Jun 01, 2015 at 10:47:30AM -0700, Dmitry Torokhov wrote:
> On Mon, Jun 01, 2015 at 05:21:11PM +0200, Pavel Machek wrote:
> >
> >
> > > > > > The 3eea8b5d68c801fec788b411582b803463834752 is just bad.
> > > > >
> > > > > You were very welcome to review this patch at the time and/or suggest
> > > > > a fix that pleases everyone.
> > > >
> > > > You should be the one that should suggest fixes, as you broke it in
> > > > the first place. But clearly you don't understand that.
> > >
> > > You actually never asked for a fix, and went head first calling this
> > > patch "bad" and asking for nothing but reverting it.
> >
> > Date: Fri, 29 May 2015 21:08:16 +0200
> > Subject: 4.1 touchscreen regression on n900 -- pinpointed [was Re:
> > linux-n900
> > ...
> > Maxime, can you suggest a fix?
>
> How about we do something like below (it needs a small edt-ft5x06 fixup
> that I'll send separately). Not tested.
>
> Thanks.
>
> --
> Dmitry
>
>
> Input: improve parsing OF parameters for touchscreens
>
> From: Dmitry Torokhov <dmitry.torokhov@gmail.com>
>
> When applying touchscreen parameters specified in device tree let's make
> sure we keep whatever setup was done by the driver and not reset the
> missing values to zero.
>
> Reported-by: Pavel Machek <pavel@ucw.cz>
> Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
> ---
> drivers/input/touchscreen/edt-ft5x06.c | 2 -
> drivers/input/touchscreen/of_touchscreen.c | 67 ++++++++++++++++++----------
> drivers/input/touchscreen/tsc2005.c | 2 -
> include/linux/input/touchscreen.h | 5 +-
> 4 files changed, 48 insertions(+), 28 deletions(-)
>
> diff --git a/drivers/input/touchscreen/edt-ft5x06.c b/drivers/input/touchscreen/edt-ft5x06.c
> index 29d179a..394b1de 100644
> --- a/drivers/input/touchscreen/edt-ft5x06.c
> +++ b/drivers/input/touchscreen/edt-ft5x06.c
> @@ -1041,7 +1041,7 @@ static int edt_ft5x06_ts_probe(struct i2c_client *client,
> 0, tsdata->num_y * 64 - 1, 0, 0);
>
> if (!pdata)
> - touchscreen_parse_of_params(input);
> + touchscreen_parse_of_params(input, true);
>
> error = input_mt_init_slots(input, MAX_SUPPORT_POINTS, INPUT_MT_DIRECT);
> if (error) {
> diff --git a/drivers/input/touchscreen/of_touchscreen.c b/drivers/input/touchscreen/of_touchscreen.c
> index b82b520..c132624 100644
> --- a/drivers/input/touchscreen/of_touchscreen.c
> +++ b/drivers/input/touchscreen/of_touchscreen.c
> @@ -14,14 +14,22 @@
> #include <linux/input/mt.h>
> #include <linux/input/touchscreen.h>
>
> -static u32 of_get_optional_u32(struct device_node *np,
> - const char *property)
> +static bool touchscreen_get_property_u32(struct device_node *np,
> + const char *property,
> + unsigned int default_value,
> + unsigned int *value)
> {
> u32 val = 0;
> + int error;
>
> - of_property_read_u32(np, property, &val);
> + error = of_property_read_u32(np, property, &val);
> + if (error) {
> + *value = default_value;
> + return false;
> + }
>
> - return val;
> + *value = val;
> + return true;

This looks good.

However, of_property_read_u32 already does the right thing here by not
update val if the property is not found.

So I guess you could just do:

*value = default_value;
return of_property_read_u32(np, property, value) ? true : false;

It looks good otherwise.

Thanks!
Maxime

--
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

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