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Subject[PATCH 4.9 072/152] HID: multitouch: do not retrieve all reports for all devices
Date
4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Benjamin Tissoires <benjamin.tissoires@redhat.com>

[ Upstream commit b897f6db3ae2cd9a42377f8b1865450f34ceff0e ]

We already have in place a quirk for Windows 8 devices, but it looks
like the Surface Cover are not conforming to it.
Given that we are only interested in 3 feature reports (the ones that
the Windows driver retrieves), we should be safe to unconditionally apply
the quirk to everybody.

In case there is an issue with a controller, we can always mark it as such
in the transport driver, and hid-multitouch won't try to retrieve the
feature report.

Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/hid/hid-multitouch.c | 76 ++++++++++++++++++++++---------------------
1 file changed, 40 insertions(+), 36 deletions(-)

--- a/drivers/hid/hid-multitouch.c
+++ b/drivers/hid/hid-multitouch.c
@@ -108,6 +108,7 @@ struct mt_device {
int cc_value_index; /* contact count value index in the field */
unsigned last_slot_field; /* the last field of a slot */
unsigned mt_report_id; /* the report ID of the multitouch device */
+ unsigned long initial_quirks; /* initial quirks state */
__s16 inputmode; /* InputMode HID feature, -1 if non-existent */
__s16 inputmode_index; /* InputMode HID feature index in the report */
__s16 maxcontact_report_id; /* Maximum Contact Number HID feature,
@@ -318,13 +319,10 @@ static void mt_get_feature(struct hid_de
u8 *buf;

/*
- * Only fetch the feature report if initial reports are not already
- * been retrieved. Currently this is only done for Windows 8 touch
- * devices.
+ * Do not fetch the feature report if the device has been explicitly
+ * marked as non-capable.
*/
- if (!(hdev->quirks & HID_QUIRK_NO_INIT_REPORTS))
- return;
- if (td->mtclass.name != MT_CLS_WIN_8)
+ if (td->initial_quirks & HID_QUIRK_NO_INIT_REPORTS)
return;

buf = hid_alloc_report_buf(report, GFP_KERNEL);
@@ -1085,36 +1083,6 @@ static int mt_probe(struct hid_device *h
}
}

- /* This allows the driver to correctly support devices
- * that emit events over several HID messages.
- */
- hdev->quirks |= HID_QUIRK_NO_INPUT_SYNC;
-
- /*
- * This allows the driver to handle different input sensors
- * that emits events through different reports on the same HID
- * device.
- */
- hdev->quirks |= HID_QUIRK_MULTI_INPUT;
- hdev->quirks |= HID_QUIRK_NO_EMPTY_INPUT;
-
- /*
- * Handle special quirks for Windows 8 certified devices.
- */
- if (id->group == HID_GROUP_MULTITOUCH_WIN_8)
- /*
- * Some multitouch screens do not like to be polled for input
- * reports. Fortunately, the Win8 spec says that all touches
- * should be sent during each report, making the initialization
- * of input reports unnecessary.
- *
- * In addition some touchpads do not behave well if we read
- * all feature reports from them. Instead we prevent
- * initial report fetching and then selectively fetch each
- * report we are interested in.
- */
- hdev->quirks |= HID_QUIRK_NO_INIT_REPORTS;
-
td = devm_kzalloc(&hdev->dev, sizeof(struct mt_device), GFP_KERNEL);
if (!td) {
dev_err(&hdev->dev, "cannot allocate multitouch data\n");
@@ -1138,6 +1106,39 @@ static int mt_probe(struct hid_device *h
if (id->vendor == HID_ANY_ID && id->product == HID_ANY_ID)
td->serial_maybe = true;

+ /*
+ * Store the initial quirk state
+ */
+ td->initial_quirks = hdev->quirks;
+
+ /* This allows the driver to correctly support devices
+ * that emit events over several HID messages.
+ */
+ hdev->quirks |= HID_QUIRK_NO_INPUT_SYNC;
+
+ /*
+ * This allows the driver to handle different input sensors
+ * that emits events through different reports on the same HID
+ * device.
+ */
+ hdev->quirks |= HID_QUIRK_MULTI_INPUT;
+ hdev->quirks |= HID_QUIRK_NO_EMPTY_INPUT;
+
+ /*
+ * Some multitouch screens do not like to be polled for input
+ * reports. Fortunately, the Win8 spec says that all touches
+ * should be sent during each report, making the initialization
+ * of input reports unnecessary. For Win7 devices, well, let's hope
+ * they will still be happy (this is only be a problem if a touch
+ * was already there while probing the device).
+ *
+ * In addition some touchpads do not behave well if we read
+ * all feature reports from them. Instead we prevent
+ * initial report fetching and then selectively fetch each
+ * report we are interested in.
+ */
+ hdev->quirks |= HID_QUIRK_NO_INIT_REPORTS;
+
ret = hid_parse(hdev);
if (ret != 0)
return ret;
@@ -1206,8 +1207,11 @@ static int mt_resume(struct hid_device *

static void mt_remove(struct hid_device *hdev)
{
+ struct mt_device *td = hid_get_drvdata(hdev);
+
sysfs_remove_group(&hdev->dev.kobj, &mt_attribute_group);
hid_hw_stop(hdev);
+ hdev->quirks = td->initial_quirks;
}

/*

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