From: Benjamin Tissoires <benjamin.tissoires@redhat.com>
To: Coiby Xu <coiby.xu@gmail.com>
Cc: "open list:HID CORE LAYER" <linux-input@vger.kernel.org>,
Jiri Kosina <jikos@kernel.org>,
linux-kernel-mentees@lists.linuxfoundation.org
Subject: Re: Advice on fixing the bug of MSFT0001:00 04F3:Touchpad being handled by hid_multitouch by mistake
Date: Fri, 4 Sep 2020 18:47:42 +0200 [thread overview]
Message-ID: <CAO-hwJJAOGNVnu1_dwXTMUyoSsNQifGFDUV6e9g96wHKmaZqSA@mail.gmail.com> (raw)
In-Reply-To: <20200904145916.nighviqyrvbm2ybx@Rk>
On Fri, Sep 4, 2020 at 4:59 PM Coiby Xu <coiby.xu@gmail.com> wrote:
>
> On Fri, Sep 04, 2020 at 10:16:51AM +0200, Benjamin Tissoires wrote:
> >Hi,
> >
> >On Tue, Aug 11, 2020 at 11:15 AM Coiby Xu <coiby.xu@gmail.com> wrote:
> >>
> >> Hi,
> >>
> >> I'm working on a touchpad device issue as reported on
> >> https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1887190.
> >>
> >> This touchpad device MSFT0001:00 04F3:Touchpad should be handled by
> >> hid_rmi. But currently hid-core.c chooses hid_multitouch by mistake,
> >>
> >> 1. When scanning this device's report descriptor, HID_DG_CONTACTID
> >> usage is found. Thus group HID_GROUP_MULTITOUCH is assigned to
> >> the device.
> >> 2. The flag HID_SCAN_FLAG_MT_WIN_8 is also found. Thus group
> >> HID_GROUP_MULTITOUCH_WIN_8 is assigned to the device.
> >> 3. hid-multitouch.c claims handling devices with the group of
> >> HID_GROUP_MULTITOUCH_WIN_8
> >>
> >> static const struct hid_device_id mt_devices[] = {
> >> /* Generic MT device */
> >> { HID_DEVICE(HID_BUS_ANY, HID_GROUP_MULTITOUCH, HID_ANY_ID, HID_ANY_ID) },
> >>
> >> /* Generic Win 8 certified MT device */
> >> { .driver_data = MT_CLS_WIN_8,
> >> HID_DEVICE(HID_BUS_ANY, HID_GROUP_MULTITOUCH_WIN_8,
> >> HID_ANY_ID, HID_ANY_ID) },
> >> { }
> >> };
> >>
> >> There are several potential solutions,
> >> - Let the device vendor fix this problem since this device's report
> >> descriptor shouldn't have the HID_DG_CONTACTID usage.
> >> - Make it a special case by setting the device's group to
> >> HID_GROUP_RMI in hid_scan_report when vendor id and product ID
> >> are matched.
> >> - hid-quirks.c seems to be designed to handle special cases, is it
> >> suitable for this case?
> >
> >AFAIU, the touchpad doesn't work at all with hid-multitouch. So I
> >guess the best is to add the VID/PID to hid-quirks.c in
> >hid_have_special_driver[], and add it to the hid-rmi driver too.
> >This way, you will ensure hid-rmi will pick up the device all the time.
> >
> >Cheers,
> >Benjamin
>
> Thank you for the advice! I have exactly adopted this approach by looking
> at commit e9287099ba6539bccb20cd791269186f3ae28b85
> ("HID: rmi: Add support for the touchpad in the Razer Blade 14 laptop")
> as an example.
>
> My previous email is a bit misleading because 0x04F3 is the vendor code
> of ELAN while hid-rmi is for the Synaptics touchpad. And actually this
> laptop model of Lenovo Legion-5 15ARH05 is shipped with both kinds of
> touchpads,
>
> - for the Synaptics touchpad, hid-rmi could almost handle it perfectly
> except the clicking is not sensitive enough. I need to let my finger
> linger on the touchpad for a while. I notice when I click on the touchpad,
> an HID report would be received by hid-recorder. But evtest couldn't receive
> any EV_ event. If hid-multitouch is handling the device, the cursor
> won't move but 2-4 finger touching events could still be received by
> evtest.
>
> - for the ELAN touchpad, only HID reporters can be read and parsed by
> hid-core then two input devices (mouse and touchpad) could created by
> hid-multitouch as seen from /proc/bus/input/devices. But hid-recorder
> could never get any HID report.
huh. So in both cases you have a buggy touchpad with hid-multitouch :(
Do both touchpads share the same VID/PID? If so, this is going to be
interesting to decide how any of those touchpad should be handled.
>
> AFAIU, isn't hid-multitouch supposed to be the implementation of Windows
> Precision Touchpad?
yes, it works for most of those. The only ones that are not working
are usually because OEM or device makers tend to do "fun" things.
> And since Precision touchpad is mandatory for
> Windows 10 notebooks and this laptop model of Lenovo Legion-5 15ARH05
> seem to have been certificated by Windows 10, does it mean by theory
> hid-multiouch could handle these two touchpad devices?
Well, it should, yes, but it clearly can not. You can try to give a
try at hid-recorder from
https://gitlab.freedesktop.org/libevdev/hid-tools. This will show what
is actually exported by the hardware before any processing by the
kernel. Maybe there is a new simple thing to do in hid-multitouch to
handle those devices.
Also, last time I heard, Synaptics dropped the use of hid-rmi in favor
of hid-multitouch. Any hid-rmi touchpad should be able to use
hid-multitouch, as this is the preferred way on Windows. But sometimes
the various teams decide to change the rules.
>
> Anyway, it seems I need to install Windows Driver Kit to capture&analyze
> HID reports to see what's happening. Or do you have any suggestion?
Unless it changed recently (I think I have seen something like that
recently), I had to write a I2C man-in-the-middle to dump the logs
from Windows. Project is at
https://github.com/bentiss/SimplePeripheralBusProbe and requires a
little bit of manual work to be able to start capturing data :(
Cheers,
Benjamin
>
> --
> Best regards,
> Coiby
>
next prev parent reply other threads:[~2020-09-04 16:47 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-11 9:14 Advice on fixing the bug of MSFT0001:00 04F3:Touchpad being handled by hid_multitouch by mistake Coiby Xu
2020-09-04 8:16 ` Benjamin Tissoires
2020-09-04 14:59 ` Coiby Xu
2020-09-04 16:47 ` Benjamin Tissoires [this message]
2020-09-10 16:37 ` Coiby Xu
2020-09-11 12:29 ` Benjamin Tissoires
2020-09-15 10:14 ` Coiby Xu
2020-09-24 7:17 ` Coiby Xu
2020-10-09 8:26 ` Coiby Xu
2020-10-09 8:55 ` Benjamin Tissoires
2020-10-14 22:09 ` Coiby Xu
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