On Fri, Oct 26, 2012 at 10:44:21AM +0200, Benjamin Tissoires wrote:
> Win8 devices are required to present the feature "Maximum Contact Number".
> Fortunately all win7 devices I've seen presents this feature.
> If the current value is 0, then, the driver can get the actual supported
> contact count by refering to the logical_max.
> This win8 specification ensures that logical_max may not be above 250.
> This also allows us to detect when devices like irtouch or stantum reports
> an obviously wrong value of 255.
>
> Signed-off-by: Benjamin Tissoires <benjamin.tissoires@xxxxxxxxx>
> ---
> drivers/hid/hid-multitouch.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/drivers/hid/hid-multitouch.c b/drivers/hid/hid-multitouch.c
> index 95562d8..41f2981 100644
> --- a/drivers/hid/hid-multitouch.c
> +++ b/drivers/hid/hid-multitouch.c
> @@ -121,6 +121,7 @@ struct mt_device {
> #define MT_CLS_GENERALTOUCH_PWT_TENFINGERS 0x0109
>
> #define MT_DEFAULT_MAXCONTACT 10
> +#define MT_MAX_MAXCONTACT 250
>
> #define MT_USB_DEVICE(v, p) HID_DEVICE(BUS_USB, HID_GROUP_MULTITOUCH, v, p)
> #define MT_BT_DEVICE(v, p) HID_DEVICE(BUS_BLUETOOTH, HID_GROUP_MULTITOUCH, v, p)
> @@ -283,6 +284,9 @@ static void mt_feature_mapping(struct hid_device *hdev,
> case HID_DG_CONTACTMAX:
> td->maxcontact_report_id = field->report->id;
> td->maxcontacts = field->value[0];
> + if (!td->maxcontacts &&
> + field->logical_maximum <= MT_MAX_MAXCONTACT)
> + td->maxcontacts = field->logical_maximum;
> if (td->mtclass.maxcontacts)
> /* check if the maxcontacts is given by the class */
> td->maxcontacts = td->mtclass.maxcontacts;
> --
> 1.7.11.7
>
Acked-by: Henrik Rydberg <rydberg@xxxxxxxxxxx>
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