Dmitry, On 08/07/15 18:08, Dmitry Torokhov wrote: > 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 You are right. I missed the fact that we don't call input_set_abs_params() in data_present is false case hence my confusion. > 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. Yes. Thanks for explaining :). cheers, -roger -- 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
