On 10/08/2015 02:40 AM, Mika Westerberg wrote:

On Wed, Oct 07, 2015 at 06:12:42PM -0700, Andrew Duggan wrote:

quoted

I can confirm that it is working on the Dell XPS 13 and the buttonpad
property is set correctly. However, I also tried it on an older non
production precision touchpad and it didn't work. It reports that it fails
to fetch feature 8 and then doesn't report any input. I'm concerned that
some of the early PTPs in some Dell and Acer systems might not work with
this change. I'll test this tomorrow on a few more systems to see if the
problem is isolated to just this one non production touchpad.

Thanks for testing.

quoted

[ 2969.222125] usb 1-1: New USB device found, idVendor=06cb, idProduct=2393
[ 2969.222128] usb 1-1: New USB device strings: Mfr=0, Product=2,
SerialNumber=0
[ 2969.222130] usb 1-1: Product: Synaptics T Pad V 01.31
[ 2974.223578] hid-multitouch 0003:06CB:2393.0008: failed to fetch feature 8
[ 2979.226037] hid-multitouch 0003:06CB:2393.0008: failed to fetch feature 8
[ 2979.226137] input: Synaptics T Pad V 01.31 UNKNOWN as /devices/pci0000:00/0000:00:14.0/usb1/1-1/1-1:1.0/0003:06CB:2393.0008/input/input34
[ 2979.226431] hid-multitouch 0003:06CB:2393.0008: input,hiddev0,hidraw2:
USB HID v1.11 Mouse [Synaptics T Pad V 01.31] on usb-0000:00:14.0-1/input0

Without the patch is it successfully retrieving feature 8?

It may be that it has HID_QUIRK_NO_INIT_REPORTS set via quirks in usbhid
which causes the driver to fetch the report in mt_feature_mapping() and
previously it did not do that.

No, this touchpad doesn't have HID_QUIRK_NO_INIT_REPORTS set and 
usbhid/hid-core.c is calling usbhid_init_reports() which is retrieving 
feature 8. But, I did some additional testing and I wasn't able to 
reproduce this issue on other systems. The failure occurs on a Dell XPS 
13 9343, but the exact same touchpad and the exact same kernel (I booted 
both systems off an external HD to ensure that the kernel and OS are 
identical) I didn't see a problem. I also tried a different USB PTP 
touchpad which didn't have an issue. Also, I tried returning in 
mt_get_feature() instead of reading the report when the report id is 8. 
When I did that everything worked.

So as of right now, it looks like a single non production USB PTP 
touchpad fails on one particular system. But, all other tests have been 
successful.

Let me know if you have any other suggestions for me to test. But, it 
seems like this failure might be fairly isolated.

Andrew