On Jul 11 2017 or thereabouts, Dmitry Torokhov wrote:
> Now that input core insists on having dev->absinfo when device claims to
> generate EV_ABS in its dev->evbit, we should not be blindly setting that
> bit.
>
> The code in question might have been needed before input_set_abs_params()
> started setting EV_ABS in device's evbit, but not anymore, and is now
> breaking devices such as SMART SPNL-6075 Touchscreen.
>
> Fixes: 6ecfe51b4082 ("Input: refuse to register absolute devices ...")
> Reported-by: Matthias Fend <Matthias.Fend@xxxxxxxxxxxxxx>
> Tested-by: Matthias Fend <Matthias.Fend@xxxxxxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>
> ---
>
> Jiri, Benjamin, I marked it for stable as it causes regressions in 4.12
> reported by users. Please take a look.
set_bit(usage->type, input->evbit); is called by hid-input.c when the
return code is positive, so we should be safe here.
Reviewed-by: Benjamin Tissoires <benjamin.tissoires@xxxxxxxxxx>
Cheers,
Benjamin
>
> drivers/hid/hid-multitouch.c | 16 ++++------------
> 1 file changed, 4 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/hid/hid-multitouch.c b/drivers/hid/hid-multitouch.c
> index 24d5b6deb571..be5bea15ce52 100644
> --- a/drivers/hid/hid-multitouch.c
> +++ b/drivers/hid/hid-multitouch.c
> @@ -595,16 +595,6 @@ static int mt_touch_input_mapping(struct hid_device *hdev, struct hid_input *hi,
> return 0;
> }
>
> -static int mt_touch_input_mapped(struct hid_device *hdev, struct hid_input *hi,
> - struct hid_field *field, struct hid_usage *usage,
> - unsigned long **bit, int *max)
> -{
> - if (usage->type == EV_KEY || usage->type == EV_ABS)
> - set_bit(usage->type, hi->input->evbit);
> -
> - return -1;
> -}
> -
> static int mt_compute_slot(struct mt_device *td, struct input_dev *input)
> {
> __s32 quirks = td->mtclass.quirks;
> @@ -905,8 +895,10 @@ static int mt_input_mapped(struct hid_device *hdev, struct hid_input *hi,
> return 0;
>
> if (field->application == HID_DG_TOUCHSCREEN ||
> - field->application == HID_DG_TOUCHPAD)
> - return mt_touch_input_mapped(hdev, hi, field, usage, bit, max);
> + field->application == HID_DG_TOUCHPAD) {
> + /* We own these mappings, tell hid-input to ignore them */
> + return -1;
> + }
>
> /* let hid-core decide for the others */
> return 0;
> --
> 2.13.2.725.g09c95d1e9-goog
>
>
> --
> Dmitry
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