Re: [PATCH] HID: ite: Only bind to keyboard USB interface on Acer SW5-012 keyboard dock

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Hi,

On 1/31/20 4:38 PM, Z R wrote:
Hi Benjamin,
hid-record for keyboard and touchpad. With Commit 8f18eca9ebc5 reverted and from unmodified kernel.

I hope it is what you asked for :-)

Currently waiting for reworked patch from Hans.

I just send you the reworked patch.

Does the recordning include pressing of the wlan on/off key (Fn + F3 I believe) ?
That is the whole reason why the special hid-ite driver is necessary.

Benjamin about the wlan on/off key. AFAICR on a press + release of the key a
single hid input report for the generic-desktop  Wireless Radio Controls group
is send. This input-report only has the one button with usage code HID_GD_RFKILL_BTN
in there and it is always 0. It is as if the input-report is only send on release
and not on press. So the hid-ite code emulates a press + release whenever the
input-report is send.

IOW the receiving of the input report is (ab)used as indication of the button
having been pressed.

Regards,

Hans



Bye for now
Zdeněk

pá 31. 1. 2020 v 15:12 odesílatel Benjamin Tissoires <benjamin.tissoires@xxxxxxxxxx <mailto:benjamin.tissoires@xxxxxxxxxx>> napsal:

    On Fri, Jan 31, 2020 at 3:04 PM Hans de Goede <hdegoede@xxxxxxxxxx <mailto:hdegoede@xxxxxxxxxx>> wrote:
     >
     > Hi,
     >
     > On 1/31/20 2:54 PM, Benjamin Tissoires wrote:
     > > On Fri, Jan 31, 2020 at 2:41 PM Hans de Goede <hdegoede@xxxxxxxxxx <mailto:hdegoede@xxxxxxxxxx>> wrote:
     > >>
     > >> Hi,
     > >>
     > >> On 1/31/20 2:10 PM, Benjamin Tissoires wrote:
     > >>> Hi Hans,
     > >>>
     > >>> On Fri, Jan 31, 2020 at 1:46 PM Hans de Goede <hdegoede@xxxxxxxxxx <mailto:hdegoede@xxxxxxxxxx>> wrote:
     > >>>>
     > >>>> Commit 8f18eca9ebc5 ("HID: ite: Add USB id match for Acer SW5-012 keyboard
     > >>>> dock") added the USB id for the Acer SW5-012's keyboard dock to the
     > >>>> hid-ite driver to fix the rfkill driver not working.
     > >>>>
     > >>>> Most keyboard docks with an ITE 8595 keyboard/touchpad controller have the
     > >>>> "Wireless Radio Control" bits which need the special hid-ite driver on the
     > >>>> second USB interface (the mouse interface) and their touchpad only supports
     > >>>> mouse emulation, so using generic hid-input handling for anything but
     > >>>> the "Wireless Radio Control" bits is fine. On these devices we simply bind
     > >>>> to all USB interfaces.
     > >>>>
     > >>>> But unlike other ITE8595 using keyboard docks, the Acer Aspire Switch 10
     > >>>> (SW5-012)'s touchpad not only does mouse emulation it also supports
     > >>>> HID-multitouch and all the keys including the "Wireless Radio Control"
     > >>>> bits have been moved to the first USB interface (the keyboard intf).
     > >>>>
     > >>>> So we need hid-ite to handle the first (keyboard) USB interface and have
     > >>>> it NOT bind to the second (mouse) USB interface so that that can be
     > >>>> handled by hid-multitouch.c and we get proper multi-touch support.
     > >>>>
     > >>>> This commit adds a match callback to hid-ite which makes it only
     > >>>> match the first USB interface when running on the Acer SW5-012,
     > >>>> fixing the regression to mouse-emulation mode introduced by adding the
     > >>>> keyboard dock USB id.
     > >>>>
     > >>>> Note the match function only does the special only bind to the first
     > >>>> USB interface on the Acer SW5-012, on other devices the hid-ite driver
     > >>>> actually must bind to the second interface as that is where the
     > >>>> "Wireless Radio Control" bits are.
     > >>>
     > >>> This is not a full review, but a couple of things that popped out
     > >>> while scrolling through the patch.
     > >>>
     > >>>>
     > >>>> Cc: stable@xxxxxxxxxxxxxxx <mailto:stable@xxxxxxxxxxxxxxx>
     > >>>> Fixes: 8f18eca9ebc5 ("HID: ite: Add USB id match for Acer SW5-012 keyboard dock")
     > >>>> Reported-by: Zdeněk Rampas <zdenda.rampas@xxxxxxxxx <mailto:zdenda.rampas@xxxxxxxxx>>
     > >>>> Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx <mailto:hdegoede@xxxxxxxxxx>>
     > >>>> ---
     > >>>>    drivers/hid/hid-ite.c | 34 ++++++++++++++++++++++++++++++++++
     > >>>>    1 file changed, 34 insertions(+)
     > >>>>
     > >>>> diff --git a/drivers/hid/hid-ite.c b/drivers/hid/hid-ite.c
     > >>>> index c436e12feb23..69a4ddfd033d 100644
     > >>>> --- a/drivers/hid/hid-ite.c
     > >>>> +++ b/drivers/hid/hid-ite.c
     > >>>> @@ -8,9 +8,12 @@
     > >>>>    #include <linux/input.h>
     > >>>>    #include <linux/hid.h>
     > >>>>    #include <linux/module.h>
     > >>>> +#include <linux/usb.h>
     > >>>>
     > >>>>    #include "hid-ids.h"
     > >>>>
     > >>>> +#define ITE8595_KBD_USB_INTF           0
     > >>>> +
     > >>>>    static int ite_event(struct hid_device *hdev, struct hid_field *field,
     > >>>>                        struct hid_usage *usage, __s32 value)
     > >>>>    {
     > >>>> @@ -37,6 +40,36 @@ static int ite_event(struct hid_device *hdev, struct hid_field *field,
     > >>>>           return 0;
     > >>>>    }
     > >>>>
     > >>>> +static bool ite_match(struct hid_device *hdev, bool ignore_special_driver)
     > >>>> +{
     > >>>> +       struct usb_interface *intf;
     > >>>> +
     > >>>> +       if (ignore_special_driver)
     > >>>> +               return false;
     > >>>> +
     > >>>> +       /*
     > >>>> +        * Most keyboard docks with an ITE 8595 keyboard/touchpad controller
     > >>>> +        * have the "Wireless Radio Control" bits which need this special
     > >>>> +        * driver on the second USB interface (the mouse interface). On
     > >>>> +        * these devices we simply bind to all USB interfaces.
     > >>>> +        *
     > >>>> +        * The Acer Aspire Switch 10 (SW5-012) is special, its touchpad
     > >>>> +        * not only does mouse emulation it also supports HID-multitouch
     > >>>> +        * and all the keys including the "Wireless Radio Control" bits
     > >>>> +        * have been moved to the first USB interface (the keyboard intf).
     > >>>> +        *
     > >>>> +        * We want the hid-multitouch driver to bind to the touchpad, so on
     > >>>> +        * the Acer SW5-012 we should only bind to the keyboard USB intf.
     > >>>> +        */
     > >>>> +       if (hdev->bus != BUS_USB || hdev->vendor != USB_VENDOR_ID_SYNAPTICS ||
     > >>>> +                    hdev->product != USB_DEVICE_ID_SYNAPTICS_ACER_SWITCH5_012)
     > >>>
     > >>> Isn't there an existing matching function we can use here, instead of
     > >>> checking each individual field?
     > >>
     > >> There is hid_match_one_id() but that is not exported (can be fixed) and it
     > >> requires a struct hid_device_id, which either requires declaring an extra
     > >> standalone struct hid_device_id for the SW5-012 kbd-dock, or hardcoding an
     > >> index into the existing hid_device_id array for the driver (with the hardcoding
     > >> being error prone, so not a good idea).
     > >>
     > >> Given the problems with using hid_match_one_id() I decided to just go with
     > >> the above.
     > >
     > > right. An other solution would be to have a local macro/function that
     > > does that. Because as soon as you start adding a quirk, an other comes
     > > right after.
     > >
     > >>
     > >> But see below.
     > >>
     > >>>
     > >>>> +               return true;
     > >>>> +
     > >>>> +       intf = to_usb_interface(hdev->dev.parent);
     > >>>
     > >>> And this is oops-prone. You need:
     > >>> - ensure hid_is_using_ll_driver(hdev, &usb_hid_driver) returns true.
     > >>> - add a dependency on USBHID in the KConfig now that you are checking
     > >>> on the USB transport layer.
     > >>>
     > >>> That being said, I would love instead:
     > >>> - to have a non USB version of this match, where you decide which
     > >>> component needs to be handled based on the report descriptor
     > >>
     > >> Actually your idea to use the desciptors is not bad, but since what
     > >> we really want is to not bind to the interface which is marked for the
     > >> hid-multitouch driver I just realized we can just check that.
     > >>
     > >> So how about:
     > >>
     > >> static bool ite_match(struct hid_device *hdev, bool ignore_special_driver)
     > >> {
     > >>           if (ignore_special_driver)
     > >>                   return false;
     > >>
     > >>           /*
     > >>            * Some keyboard docks with an ITE 8595 keyboard/touchpad controller
     > >>            * support the HID multitouch protocol for the touchpad, in that
     > >>            * case the "Wireless Radio Control" bits which we care about are
     > >>            * on the other interface; and we should not bind to the multitouch
     > >>            * capable interface as that breaks multitouch support.
     > >>            */
     > >>           return hdev->group != HID_GROUP_MULTITOUCH_WIN_8;
     > >> }
     > >
     > > Yep, I like that very much :)
     >
     > Actually if we want to check the group and there are only 2 interfaces we do
     > not need to use the match callback at all, w e can simply match on the
     > group of the interface which we do want:
     >
     > diff --git a/drivers/hid/hid-ite.c b/drivers/hid/hid-ite.c
     > index db0f35be5a8b..21bd48f16033 100644
     > --- a/drivers/hid/hid-ite.c
     > +++ b/drivers/hid/hid-ite.c
     > @@ -56,8 +56,9 @@ static const struct hid_device_id ite_devices[] = {
     >         { HID_USB_DEVICE(USB_VENDOR_ID_ITE, USB_DEVICE_ID_ITE8595) },
     >         { HID_USB_DEVICE(USB_VENDOR_ID_258A, USB_DEVICE_ID_258A_6A88) },
     >         /* ITE8595 USB kbd ctlr, with Synaptics touchpad connected to it. */
     > -       { HID_USB_DEVICE(USB_VENDOR_ID_SYNAPTICS,
     > -                        USB_DEVICE_ID_SYNAPTICS_ACER_SWITCH5_012) },
     > +       { HID_DEVICE(BUS_USB, HID_GROUP_GENERIC,
     > +                    USB_VENDOR_ID_SYNAPTICS,
     > +                    USB_DEVICE_ID_SYNAPTICS_ACER_SWITCH5_012) },
     >         { }
     >   };
     >   MODULE_DEVICE_TABLE(hid, ite_devices);
     >
     > Much cleaner

    yep

     > (and now I don't need to write a test, which is always
     > a good motivation to come up with a cleaner solution :)

    Hehe, too bad, you already picked up my curiosity on this one, and I
    really would like to see the report descriptors and some events of the
    keys that are fixed by hid-ite.c.
    <with a low voice>This will be a hard requirement to accept this patch </joke>.

    More seriously, Zdeněk, can you run hid-recorder from
    https://gitlab.freedesktop.org/libevdev/hid-tools/ and provide me the
    report descriptor for all of your ITE HID devices? I'll add the
    matching tests in hid-tools and be sure we do not regress in the
    future.

     >
     > Let me turn this into a proper patch and then I will send that to
     > Zdeněk (off-list) for him to test (note don't worry if you do
     > not have time to test this weekend, then I'll do it on Monday).
     >
     > Regards,
     >
     > Hans
     >
     > p.s.
     >
     > 1. My train is approaching Brussels (Fosdem) so my email response
     > time will soon become irregular.

    How dare you? :)

     >
     > 2. Benjamin will you be at Fosdem too ?
     >

    Unfortunately no. Already got my quota of meeting people for this year
    between Kernel Recipes in September, XDC in October and LCA last week.
    So I need to keep in a quiet environment for a little bit :)

    Cheers,
    Benjamin





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