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 fetch for Win8 devices. It should not be needed anyway according to [1] because the two "GET" feature reports for these devices are about device capabilities and Win8 certification status which are not related to input events. [1] https://msdn.microsoft.com/en-us/library/windows/hardware/dn467314(v=vs.85).aspx Signed-off-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx> --- drivers/hid/hid-multitouch.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/drivers/hid/hid-multitouch.c b/drivers/hid/hid-multitouch.c index 426b2f1a3450..1911f7698511 100644 --- a/drivers/hid/hid-multitouch.c +++ b/drivers/hid/hid-multitouch.c @@ -1020,14 +1020,16 @@ static int mt_probe(struct hid_device *hdev, const struct hid_device_id *id) /* * Handle special quirks for Windows 8 certified devices. */ - if (id->group == HID_GROUP_MULTITOUCH_WIN_8) + 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. + * and feature reports. Fortunately, the Win8 spec says that all + * touches should be sent during each report, making the + * initialization of input reports unnecessary. */ 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) { -- 2.5.1 -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
