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SubjectRe: [PATCH] HID: multitouch: handle faulty Elo touch device
On Tue, May 21, 2019 at 3:38 PM Benjamin Tissoires
<benjamin.tissoires@redhat.com> wrote:
>
> Since kernel v5.0, one single win8 touchscreen device failed.
> And it turns out this is because it reports 2 InRange usage per touch.
>
> It's a first, and I *really* wonder how this was allowed by Microsoft in
> the first place. But IIRC, Breno told me this happened *after* a firmware
> upgrade...
>
> Anyway, better be safe for those crappy devices, and make sure we have
> a full slot before jumping to the next.
> This won't prevent all crappy devices to fail here, but at least we will
> have a safeguard as long as the contact ID and the X and Y coordinates
> are placed in the report after the grabage.

Grmbl, I forgot:
Fixes: 01eaac7e5713 ("HID: multitouch: remove one copy of values")
CC: stable@vger.kernel.org # v5.0+

Cheers,
Benjamin

>
> Reported-and-tested-by: Breno Leitao <leitao@debian.org>
> Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
> ---
> drivers/hid/hid-multitouch.c | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/drivers/hid/hid-multitouch.c b/drivers/hid/hid-multitouch.c
> index ef635964cfe1..a344a3cf5398 100644
> --- a/drivers/hid/hid-multitouch.c
> +++ b/drivers/hid/hid-multitouch.c
> @@ -642,6 +642,13 @@ static void mt_store_field(struct hid_device *hdev,
> if (*target != DEFAULT_TRUE &&
> *target != DEFAULT_FALSE &&
> *target != DEFAULT_ZERO) {
> + if (usage->contactid == DEFAULT_ZERO ||
> + usage->x == DEFAULT_ZERO ||
> + usage->y == DEFAULT_ZERO) {
> + hid_dbg(hdev,
> + "ignoring duplicate usage on incomplete");
> + return;
> + }
> usage = mt_allocate_usage(hdev, application);
> if (!usage)
> return;
> --
> 2.19.2
>

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