From: Benjamin Bara <[email protected]>
When the optional fields "pressure_min" and "pressure_max" are not set,
both fall back to 0, which results to the following libinput error:
ADS7846 Touchscreen: kernel bug: device has min == max on ABS_PRESSURE
Avoid it by only setting ABS_PRESSURE if the values differ.
Signed-off-by: Benjamin Bara <[email protected]>
---
drivers/input/touchscreen/ads7846.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/input/touchscreen/ads7846.c b/drivers/input/touchscreen/ads7846.c
index faea40dd66d0..2535424a5630 100644
--- a/drivers/input/touchscreen/ads7846.c
+++ b/drivers/input/touchscreen/ads7846.c
@@ -1281,7 +1281,7 @@ static int ads7846_probe(struct spi_device *spi)
pdata->y_min ? : 0,
pdata->y_max ? : MAX_12BIT,
0, 0);
- if (ts->model != 7845)
+ if (ts->model != 7845 && pdata->pressure_min != pdata->pressure_max)
input_set_abs_params(input_dev, ABS_PRESSURE,
pdata->pressure_min, pdata->pressure_max, 0, 0);
---
base-commit: 451cc82bd11eb6a374f4dbcfc1cf007eafea91ab
change-id: 20230727-ads7846-pressure-05edfb01887f
Best regards,
--
Benjamin Bara <[email protected]>
Hi Benjamin,
On Thu, Jul 27, 2023 at 05:19:57PM +0200, Benjamin Bara wrote:
> From: Benjamin Bara <[email protected]>
>
> When the optional fields "pressure_min" and "pressure_max" are not set,
> both fall back to 0, which results to the following libinput error:
>
> ADS7846 Touchscreen: kernel bug: device has min == max on ABS_PRESSURE
>
> Avoid it by only setting ABS_PRESSURE if the values differ.
What is the benefit of silently continuing without reporting pressure on
models that do support pressure readings, vs. using libinput's errors as
signal to adjust DT?
>
> Signed-off-by: Benjamin Bara <[email protected]>
> ---
> drivers/input/touchscreen/ads7846.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/input/touchscreen/ads7846.c b/drivers/input/touchscreen/ads7846.c
> index faea40dd66d0..2535424a5630 100644
> --- a/drivers/input/touchscreen/ads7846.c
> +++ b/drivers/input/touchscreen/ads7846.c
> @@ -1281,7 +1281,7 @@ static int ads7846_probe(struct spi_device *spi)
> pdata->y_min ? : 0,
> pdata->y_max ? : MAX_12BIT,
> 0, 0);
> - if (ts->model != 7845)
> + if (ts->model != 7845 && pdata->pressure_min != pdata->pressure_max)
> input_set_abs_params(input_dev, ABS_PRESSURE,
> pdata->pressure_min, pdata->pressure_max, 0, 0);
>
>
> ---
> base-commit: 451cc82bd11eb6a374f4dbcfc1cf007eafea91ab
> change-id: 20230727-ads7846-pressure-05edfb01887f
>
> Best regards,
> --
> Benjamin Bara <[email protected]>
>
Thanks.
--
Dmitry
Hi Dmitry,
thank you for the feedback!
On Thu, 27 Jul 2023 at 22:39, Dmitry Torokhov <[email protected]> wrote:
> On Thu, Jul 27, 2023 at 05:19:57PM +0200, Benjamin Bara wrote:
> > From: Benjamin Bara <[email protected]>
> >
> > When the optional fields "pressure_min" and "pressure_max" are not set,
> > both fall back to 0, which results to the following libinput error:
> >
> > ADS7846 Touchscreen: kernel bug: device has min == max on ABS_PRESSURE
> >
> > Avoid it by only setting ABS_PRESSURE if the values differ.
>
> What is the benefit of silently continuing without reporting pressure on
> models that do support pressure readings, vs. using libinput's errors as
> signal to adjust DT?
With the current implementation, libinput rejects the device [1] when an
optional device-tree field is not set, which leads to a "non-functional" device.
But you are right, silently continuing might also not be the best option...
I could provide a v2 where the maximum is set to a fallback value (~0) and a
warning is printed that the pressure is not set and therefore a fallback value
is used, to signal the user to adjust the DT.
What do you think about that?
Best regards
Benjamin
[1] https://gitlab.freedesktop.org/libinput/libinput/-/blob/1.23.0/src/evdev.c?ref_type=tags#L1816