Patch "HID: multitouch: Fetch feature reports on demand for Win8 devices" has been added to the 4.3-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    HID: multitouch: Fetch feature reports on demand for Win8 devices

to the 4.3-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     hid-multitouch-fetch-feature-reports-on-demand-for-win8-devices.patch
and it can be found in the queue-4.3 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 6d4f5440a3a2bb2e9d0d582bbf98234e9e9bb095 Mon Sep 17 00:00:00 2001
From: Mika Westerberg <mika.westerberg@linux.intel.com>
Date: Wed, 7 Oct 2015 15:33:43 +0300
Subject: HID: multitouch: Fetch feature reports on demand for Win8 devices

From: Mika Westerberg <mika.westerberg@linux.intel.com>

commit 6d4f5440a3a2bb2e9d0d582bbf98234e9e9bb095 upstream.

Some newer Intel Skylake based Dell laptops with Win8 precision touchpad
fail when initial feature reports are fetched from it. Below is an example
output with some additional debug included:

 i2c_hid i2c-DLL0704:01: Fetching the HID descriptor
 i2c_hid i2c-DLL0704:01: __i2c_hid_command: cmd=20 00
 i2c_hid i2c-DLL0704:01: HID Descriptor: 1e 00 00 01 99 02 21 00 24 ...
 ...
 i2c_hid i2c-DLL0704:01: i2c_hid_get_report
 i2c_hid i2c-DLL0704:01: __i2c_hid_command: cmd=22 00 38 02 23 00
 i2c_hid i2c-DLL0704:01: report (len=4): 04 00 08 05
 i2c_hid i2c-DLL0704:01: report id 13
 i2c_hid i2c-DLL0704:01: i2c_hid_get_report
 i2c_hid i2c-DLL0704:01: __i2c_hid_command: cmd=22 00 3d 02 23 00
 i2c_hid i2c-DLL0704:01: failed to retrieve report from device.
 i2c_hid i2c-DLL0704:01: report id 7
 i2c_hid i2c-DLL0704:01: i2c_hid_get_report
 i2c_hid i2c-DLL0704:01: __i2c_hid_command: cmd=22 00 37 02 23 00
 i2c_hid i2c-DLL0704:01: report (len=259): 03 01 07 fc 28 fe 84 40 ...
 i2c_hid i2c-DLL0704:01: report id 4
 i2c_hid i2c-DLL0704:01: i2c_hid_get_report
 i2c_hid i2c-DLL0704:01: __i2c_hid_command: cmd=22 00 34 02 23 00

We manage to fetch few reports but then the touchpad dies:

 i2c_designware i2c_designware.1: i2c_dw_handle_tx_abort: lost arbitration
 i2c_hid i2c-DLL0704:01: failed to retrieve report from device.

it eventually pulls the whole I2C bus low:

 i2c_designware i2c_designware.1: controller timed out
 i2c_hid i2c-DLL0704:01: failed to set a report to device.

Fix this by preventing initial feature report retrieval for Win8 devices.
Instead we fetch reports as needed in mt_feature_mapping(). This prevents
fetching reports which might cause problems with the device in question.

Suggested-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Tested-by: Seth Forshee <seth.forshee@canonical.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/hid/hid-multitouch.c |   45 ++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 44 insertions(+), 1 deletion(-)

--- a/drivers/hid/hid-multitouch.c
+++ b/drivers/hid/hid-multitouch.c
@@ -309,6 +309,41 @@ static struct attribute_group mt_attribu
 	.attrs = sysfs_attrs
 };
 
+static void mt_get_feature(struct hid_device *hdev, struct hid_report *report)
+{
+	struct mt_device *td = hid_get_drvdata(hdev);
+	int ret, size = hid_report_len(report);
+	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.
+	 */
+	if (!(hdev->quirks & HID_QUIRK_NO_INIT_REPORTS))
+		return;
+	if (td->mtclass.name != MT_CLS_WIN_8)
+		return;
+
+	buf = hid_alloc_report_buf(report, GFP_KERNEL);
+	if (!buf)
+		return;
+
+	ret = hid_hw_raw_request(hdev, report->id, buf, size,
+				 HID_FEATURE_REPORT, HID_REQ_GET_REPORT);
+	if (ret < 0) {
+		dev_warn(&hdev->dev, "failed to fetch feature %d\n",
+			 report->id);
+	} else {
+		ret = hid_report_raw_event(hdev, HID_FEATURE_REPORT, buf,
+					   size, 0);
+		if (ret)
+			dev_warn(&hdev->dev, "failed to report feature\n");
+	}
+
+	kfree(buf);
+}
+
 static void mt_feature_mapping(struct hid_device *hdev,
 		struct hid_field *field, struct hid_usage *usage)
 {
@@ -327,6 +362,8 @@ static void mt_feature_mapping(struct hi
 
 		break;
 	case HID_DG_CONTACTMAX:
+		mt_get_feature(hdev, field->report);
+
 		td->maxcontact_report_id = field->report->id;
 		td->maxcontacts = field->value[0];
 		if (!td->maxcontacts &&
@@ -343,6 +380,7 @@ static void mt_feature_mapping(struct hi
 			break;
 		}
 
+		mt_get_feature(hdev, field->report);
 		if (field->value[usage->usage_index] == MT_BUTTONTYPE_CLICKPAD)
 			td->is_buttonpad = true;
 
@@ -1026,8 +1064,13 @@ static int mt_probe(struct hid_device *h
 		 * 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_INPUT_REPORTS;
+		hdev->quirks |= HID_QUIRK_NO_INIT_REPORTS;
 
 	td = devm_kzalloc(&hdev->dev, sizeof(struct mt_device), GFP_KERNEL);
 	if (!td) {


Patches currently in stable-queue which might be from mika.westerberg@linux.intel.com are

queue-4.3/hid-multitouch-fetch-feature-reports-on-demand-for-win8-devices.patch