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

Dmitry Torokhov
2015-06-01T21:32:27Z

On Mon, Jun 01, 2015 at 11:22:26PM +0200, Maxime Ripard wrote:
> 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.

I know but it is not documented anywhere (as far as I know) so I'd
rather not rely on the implementation detail that might change in the
future. This is not a hot path so extra assignment should not hurt.

Thanks.

--
Dmitry