The previous implementation registered a pointer towards hid-core
to the value of contact count. This is not safe and may be difficult
to debug if hid-core ever changes its implementation.
The use of regular indexes is a better choice.
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@xxxxxxxxx>
---
drivers/hid/hid-multitouch.c | 19 +++++++++++++------
1 file changed, 13 insertions(+), 6 deletions(-)
diff --git a/drivers/hid/hid-multitouch.c b/drivers/hid/hid-multitouch.c
index 28af54f..e22fbd3 100644
--- a/drivers/hid/hid-multitouch.c
+++ b/drivers/hid/hid-multitouch.c
@@ -84,7 +84,8 @@ struct mt_device {
struct mt_class mtclass; /* our mt device class */
struct mt_fields *fields; /* temporary placeholder for storing the
multitouch fields */
- __s32 *contactcount; /* contact count value in the report */
+ int cc_index; /* contact count field index in the report */
+ int cc_value_index; /* contact count value index in the field */
unsigned last_field_index; /* last field index of the report */
unsigned last_slot_field; /* the last field of a slot */
unsigned mt_report_id; /* the report ID of the multitouch device */
@@ -269,7 +270,7 @@ static ssize_t mt_set_quirks(struct device *dev,
td->mtclass.quirks = val;
- if (!td->contactcount)
+ if (td->cc_index < 0)
td->mtclass.quirks &= ~MT_QUIRK_CONTACT_CNT_ACCURATE;
return count;
@@ -483,7 +484,8 @@ static int mt_input_mapping(struct hid_device *hdev, struct hid_input *hi,
td->last_field_index = field->index;
return 1;
case HID_DG_CONTACTCOUNT:
- td->contactcount = field->value + usage->usage_index;
+ td->cc_index = field->index;
+ td->cc_value_index = usage->usage_index;
td->last_field_index = field->index;
return 1;
case HID_DG_CONTACTMAX:
@@ -701,8 +703,12 @@ static void mt_report(struct hid_device *hid, struct hid_report *report)
* Includes multi-packet support where subsequent
* packets are sent with zero contactcount.
*/
- if (td->contactcount && *td->contactcount)
- td->num_expected = *td->contactcount;
+ if (td->cc_index >= 0) {
+ struct hid_field *field = report->field[td->cc_index];
+ int value = field->value[td->cc_value_index];
+ if (value)
+ td->num_expected = value;
+ }
for (r = 0; r < report->maxfield; r++) {
field = report->field[r];
@@ -786,7 +792,7 @@ static void mt_post_parse(struct mt_device *td)
td->last_slot_field = f->usages[field_count_per_touch - 1];
}
- if (!td->contactcount)
+ if (td->cc_index < 0)
cls->quirks &= ~MT_QUIRK_CONTACT_CNT_ACCURATE;
}
@@ -845,6 +851,7 @@ static int mt_probe(struct hid_device *hdev, const struct hid_device_id *id)
td->mtclass = *mtclass;
td->inputmode = -1;
td->maxcontact_report_id = -1;
+ td->cc_index = -1;
hid_set_drvdata(hdev, td);
td->fields = kzalloc(sizeof(struct mt_fields), GFP_KERNEL);
--
1.8.1
--
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