On Wed, Jul 08, 2015 at 10:59:04AM +0300, Roger Quadros wrote: > Dmitry, > > On 07/07/15 19:25, Dmitry Torokhov wrote: > >Hi Roger, > > > >On Tue, Jul 07, 2015 at 12:37:31PM +0300, Roger Quadros wrote: > >>Hi Dmitry, > >> > >>On 07/07/15 03:27, Dmitry Torokhov wrote: > >>>The binding specification says that "touchscreen-size-x" and "-y" specify > >>>horizontal and vertical resolution of the touchscreen and therefore maximum > >>>absolute coordinates should be reduced by 1 since we are starting with 0. > >>> > >>>Signed-off-by: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx> > >>>--- > >>> drivers/input/touchscreen/of_touchscreen.c | 10 ++++++---- > >>> 1 file changed, 6 insertions(+), 4 deletions(-) > >>> > >>>diff --git a/drivers/input/touchscreen/of_touchscreen.c b/drivers/input/touchscreen/of_touchscreen.c > >>>index 759cf4b..50bc0f2 100644 > >>>--- a/drivers/input/touchscreen/of_touchscreen.c > >>>+++ b/drivers/input/touchscreen/of_touchscreen.c > >>>@@ -71,23 +71,25 @@ void touchscreen_parse_of_params(struct input_dev *dev, bool multitouch) > >>> > >>> axis = multitouch ? ABS_MT_POSITION_X : ABS_X; > >>> data_present = touchscreen_get_prop_u32(np, "touchscreen-size-x", > >>>- input_abs_get_max(dev, axis), > >>>+ input_abs_get_max(dev, > >>>+ axis) + 1, > >> > >>Why do we need to pass default_value to touchscreen_get_prop_u32()? > >>If the property doesn't exist we are not updating the parameter > >>anyway right? > > > >The binding can specify max, fuzz, both, or neither. If only one is > >specified we do not want to "undo" whatever the driver did (for example > > why not? At least that is not what touchscreen_parse_properties() does. > It will update the touchscreen params if any one of the DT property > is present. Yes, but while keeping the old properties (max, fuzz) intact if they have not been specified in dts. That is why we are passing default value to touchscreen_get_prop_u32. > > >tsc2005 sets up the default maximums before trying to parse OF), so we > >fetch the current value and pass it on as default one. > > This is what would happen in tsc2005 case > > -driver first sets ABS_X_max to 0xfff and ABS_Y_max to 0xfff. > -calls touchscreen_parse_properties() > -which calls touchscreen_get_prop_u32(dev, "touchscreen-size-x", > 0xfff+1, &maximum) > -if DT properties are missing, touchscreen_get_prop_u32() changes > ABS_X_max to 0x1000 and returns false. > - as data_present is false we don't do a -1 and so we have ABS_X_max > changed to 0x1000. If data_present is false we do not call input_set_abs_params() at all ans so nothing changes in input device settings. Now, if fuzz would be set up (but size was not) we would be calling input_set_abs_params(), but given that we subtract 1 from maximum returned by touchscreen_get_prop_u32() we'd be setting input_set_abs_params(input, ABS_X, 0, 0x1000 - 1, fuzz) thus preserving 0xfff value set by the driver. > > This doesn't look right. > > So IMO default_value parameter can be removed from > touchscreen_get_prop_u32() to make things simpler. > > If the property doesn't exist it will not change *value and return false. But it will change if one of the properties set. For example, if you set fuzz but not size. Thanks. -- Dmitry -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
