RE: [PATCH] Partially revert "HID: generic: create one input report per application type"

From: Junge, Terry
Date: Fri Aug 31 2018 - 13:48:49 EST


For what it's worth the Report Descriptor is a little questionable
which could be causing the collection to split in two

>-----Original Message-----
>From: linux-input-owner@xxxxxxxxxxxxxxx [mailto:linux-input-
>owner@xxxxxxxxxxxxxxx] On Behalf Of Benjamin Tissoires
>Sent: Friday, August 31, 2018 2:36 AM
>To: Jiri Kosina <jikos@xxxxxxxxxx>; Dmitry Torokhov
><dmitry.torokhov@xxxxxxxxx>
>Cc: linux-input@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; Benjamin
>Tissoires <benjamin.tissoires@xxxxxxxxxx>; stable@xxxxxxxxxxxxxxx
>Subject: [PATCH] Partially revert "HID: generic: create one input report per
>application type"
>
>This partially reverts commit f07b3c1da92db108662f99417a212fc1eddc44d1.
>
>It looks like some mice are not correctly treated by
>HID_QUIRK_INPUT_PER_APP. Those mice have the following
>report descriptor:
>
>0x05, 0x01, // Usage Page (Generic Desktop) 0
>0x09, 0x02, // Usage (Mouse) 2
>0xa1, 0x01, // Collection (Application) 4
>0x85, 0x01, // Report ID (1) 6
>0x09, 0x01, // Usage (Pointer) 8

This physical collection is associated with Generic Desktop:Pointer (0x0001:0x0001)

>0xa1, 0x00, // Collection (Physical) 10
>0x95, 0x05, // Report Count (5) 12
>0x75, 0x01, // Report Size (1) 14
>0x05, 0x09, // Usage Page (Button) 16

We are now in the Button page

>0x19, 0x01, // Usage Minimum (1) 18
>0x29, 0x05, // Usage Maximum (5) 20
>0x15, 0x00, // Logical Minimum (0) 22
>0x25, 0x01, // Logical Maximum (1) 24
>0x81, 0x02, // Input (Data,Var,Abs) 26
>...
>0xc0, // End Collection 57
>0x85, 0x02, // Report ID (2) 58
>0x09, 0x01, // Usage (Consumer Control) 60

This physical collection is associated with Button:Button 1 (0x0009:0x0001)
not Generic Desktop:Pointer (0x0001:0x0001)

>0xa1, 0x00, // Collection (Physical) 62
>0x75, 0x0c, // Report Size (12) 64
>0x95, 0x02, // Report Count (2) 66
>0x05, 0x01, // Usage Page (Generic Desktop) 68

Now we're back in the Generic Desktop page

>0x09, 0x30, // Usage (X) 70
>0x09, 0x31, // Usage (Y) 72
>0x16, 0x01, 0xf8, // Logical Minimum (-2047) 74
>0x26, 0xff, 0x07, // Logical Maximum (2047) 77
>0x81, 0x06, // Input (Data,Var,Rel) 80
>0xc0, // End Collection 82
>0xc0, // End Collection 83
>...
>
>Both the cursor position and the buttons are located in the
>same application collection (Mouse) and the kernel should
>only create one input device for those.
>
>However, for an undetermined reason, the kernel splits the
>device in 2, making systemd not tagging the second mouse
>with the coordinates only as a mouse. And then userspace
>ignores it which leads to a mouse where only the buttons
>are working.
>
>Until the quirk gets properly fixed, we should probably
>revert applying it to all of the generic devices and
>re-enable it when the root reason has been found.
>
>link: https://bugzilla.kernel.org/show_bug.cgi?id=200847
>link: https://bugzilla.kernel.org/show_bug.cgi?id=200849
>link: https://bugs.archlinux.org/task/59699
>link: https://github.com/NixOS/nixpkgs/issues/45165
>
>Cc: stable@xxxxxxxxxxxxxxx # v4.18+
>Signed-off-by: Benjamin Tissoires <benjamin.tissoires@xxxxxxxxxx>
>---
> drivers/hid/hid-generic.c | 15 ---------------
> 1 file changed, 15 deletions(-)
>
>diff --git a/drivers/hid/hid-generic.c b/drivers/hid/hid-generic.c
>index 3b6eccbc2519..c25b4718de44 100644
>--- a/drivers/hid/hid-generic.c
>+++ b/drivers/hid/hid-generic.c
>@@ -56,20 +56,6 @@ static bool hid_generic_match(struct hid_device *hdev,
> return true;
> }
>
>-static int hid_generic_probe(struct hid_device *hdev,
>- const struct hid_device_id *id)
>-{
>- int ret;
>-
>- hdev->quirks |= HID_QUIRK_INPUT_PER_APP;
>-
>- ret = hid_parse(hdev);
>- if (ret)
>- return ret;
>-
>- return hid_hw_start(hdev, HID_CONNECT_DEFAULT);
>-}
>-
> static const struct hid_device_id hid_table[] = {
> { HID_DEVICE(HID_BUS_ANY, HID_GROUP_ANY, HID_ANY_ID,
>HID_ANY_ID) },
> { }
>@@ -80,7 +66,6 @@ static struct hid_driver hid_generic = {
> .name = "hid-generic",
> .id_table = hid_table,
> .match = hid_generic_match,
>- .probe = hid_generic_probe,
> };
> module_hid_driver(hid_generic);
>
>--
>2.14.3
>
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