HID: multitouch: Fetch feature reports on demand for Win8 devices (6d4f5440) · Commits · 戴 / test

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>

drivers/hid/hid-multitouch.c

+44 −1

Original line number	Diff line number	Diff line
		@@ -309,6 +309,41 @@ static struct attribute_group mt_attribute_group = {
		.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 hid_device *hdev,

		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 hid_device *hdev,
		break;
		}

		mt_get_feature(hdev, field->report);
		if (field->value[usage->usage_index] == MT_BUTTONTYPE_CLICKPAD)
		td->is_buttonpad = true;

		@@ -1029,8 +1067,13 @@ static int mt_probe(struct hid_device hdev, const struct hid_device_id id)
		* 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) {

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