Re: [PATCH] HID: fix A4Tech horizontal scrolling

From: Igor Kushnir
Date: Fri May 03 2019 - 05:37:10 EST


Hi Benjamin,

On 5/3/19 10:36 AM, Benjamin Tissoires wrote:
Hi,

On Thu, May 2, 2019 at 11:37 PM BÅaÅej SzczygieÅ <spaz16@xxxxx> wrote:

Since recent high resolution scrolling changes the A4Tech driver must
check for the "REL_WHEEL_HI_RES" usage code.

Fixes: 2dc702c991e3774af9d7ce410eef410ca9e2357e (HID: input: use the
Resolution Multiplier for high-resolution scrolling)

Signed-off-by: BÅaÅej SzczygieÅ <spaz16@xxxxx>

Thanks for the patch. I do not doubt this fixes the issues, but I
still wonder if we should not export REL_HWHEEL_HI_RES instead of
REL_HWHEEL events.


If you mean exporting REL_HWHEEL_HI_RES instead of REL_HWHEEL from
hid-a4tech.c, then it makes sense to me, though I do not know the code
well enough to be certain.

BÅaÅej and I have discussed the bug and the patch here:
https://bugzilla.kernel.org/show_bug.cgi?id=203369

In summary: the patch fixes the bug for both our mice;
the documentation in input/event-codes.rst states that
REL_WHEEL, REL_HWHEEL "are legacy codes and REL_WHEEL_HI_RES and
REL_HWHEEL_HI_RES should be preferred where available."

Also, I can not figure out how the events are processed by the kernel.
Could you attach a hid-recorder dump of the mouse wheels with
hid-recorder from https://gitlab.freedesktop.org/libevdev/hid-tools ?

This should give me a better view of the mouse, and I could also add
it to the regression tests I am running for each commit.

Cheers,
Benjamin

After launching hid-recorder for my A4Tech WOP-49Z mouse under kernel
5.0.10 patched with BÅaÅej's patch I:
* scrolled the vertical wheel down ("Wheel: -1");
* scrolled the vertical wheel up ("Wheel: 1");
* scrolled the horizontal wheel "left" ("Wheel: -1");
* scrolled the horizontal wheel "right" ("Wheel: 1").
Note that the horizontal wheel is physically scrolled just like the
vertical one in this mouse (forward/back), so "left" and "right" are the
effects these scrollings make in applications when the kernel supports
the mouse properly.

$ sudo ./hid-recorder /dev/hidraw1
# A4Tech PS/2+USB Mouse
# 0x05, 0x01, // Usage Page (Generic Desktop) 0
# 0x09, 0x02, // Usage (Mouse) 2
# 0xa1, 0x01, // Collection (Application) 4
# 0x09, 0x01, // Usage (Pointer) 6
# 0xa1, 0x00, // Collection (Physical) 8
# 0x05, 0x09, // Usage Page (Button) 10
# 0x19, 0x01, // Usage Minimum (1) 12
# 0x29, 0x07, // Usage Maximum (7) 14
# 0x15, 0x00, // Logical Minimum (0) 16
# 0x25, 0x01, // Logical Maximum (1) 18
# 0x75, 0x01, // Report Size (1) 20
# 0x95, 0x07, // Report Count (7) 22
# 0x81, 0x02, // Input (Data,Var,Abs) 24
# 0x75, 0x01, // Report Size (1) 26
# 0x95, 0x01, // Report Count (1) 28
# 0x81, 0x01, // Input (Cnst,Arr,Abs) 30
# 0x05, 0x01, // Usage Page (Generic Desktop) 32
# 0x09, 0x30, // Usage (X) 34
# 0x09, 0x31, // Usage (Y) 36
# 0x09, 0x38, // Usage (Wheel) 38
# 0x15, 0x81, // Logical Minimum (-127) 40
# 0x25, 0x7f, // Logical Maximum (127) 42
# 0x75, 0x08, // Report Size (8) 44
# 0x95, 0x03, // Report Count (3) 46
# 0x81, 0x06, // Input (Data,Var,Rel) 48
# 0xc0, // End Collection 50
# 0xc0, // End Collection 51
#
R: 52 05 01 09 02 a1 01 09 01 a1 00 05 09 19 01 29 07 15 00 25 01 75 01 95 07 81 02 75 01 95 01 81 01 05 01 09 30 09 31 09 38 15 81 25 7f 75 08 95 03 81 06 c0 c0
N: A4Tech PS/2+USB Mouse
I: 3 09da 0006
# Button: 0 0 0 0 0 0 0 | # | X: 0 | Y: 0 | Wheel: -1
E: 000000.000000 4 00 00 00 ff
# Button: 0 0 0 0 0 0 0 | # | X: 0 | Y: 0 | Wheel: -1
E: 000000.071952 4 00 00 00 ff
# Button: 0 0 0 0 0 0 0 | # | X: 0 | Y: 0 | Wheel: -1
E: 000000.159957 4 00 00 00 ff
# Button: 0 0 0 0 0 0 0 | # | X: 0 | Y: 0 | Wheel: 1
E: 000002.912232 4 00 00 00 01
# Button: 0 0 0 0 0 0 0 | # | X: 0 | Y: 0 | Wheel: 1
E: 000002.952190 4 00 00 00 01
# Button: 0 0 0 0 0 0 0 | # | X: 0 | Y: 0 | Wheel: 1
E: 000004.512359 4 00 00 00 01
# Button: 0 0 0 0 0 0 0 | # | X: 0 | Y: 0 | Wheel: 1
E: 000004.584332 4 00 00 00 01
# Button: 0 0 0 0 0 0 1 | # | X: 0 | Y: 0 | Wheel: -1
E: 000007.528626 4 40 00 00 ff
# Button: 0 0 0 0 0 0 1 | # | X: 0 | Y: 0 | Wheel: -1
E: 000007.568577 4 40 00 00 ff
# Button: 0 0 0 0 0 0 1 | # | X: 0 | Y: 0 | Wheel: -1
E: 000008.256395 4 40 00 00 ff
# Button: 0 0 0 0 0 0 1 | # | X: 0 | Y: 0 | Wheel: -1
E: 000008.336669 4 40 00 00 ff
# Button: 0 0 0 0 0 0 1 | # | X: 0 | Y: 0 | Wheel: -1
E: 000008.400649 4 40 00 00 ff
# Button: 0 0 0 0 0 0 1 | # | X: 0 | Y: 0 | Wheel: 1
E: 000010.936908 4 40 00 00 01
# Button: 0 0 0 0 0 0 1 | # | X: 0 | Y: 0 | Wheel: 1
E: 000010.984864 4 40 00 00 01
# Button: 0 0 0 0 0 0 1 | # | X: 0 | Y: 0 | Wheel: 1
E: 000011.056897 4 40 00 00 01
# Button: 0 0 0 0 0 0 1 | # | X: 0 | Y: 0 | Wheel: 1
E: 000011.528936 4 40 00 00 01
# Button: 0 0 0 0 0 0 1 | # | X: 0 | Y: 0 | Wheel: 1
E: 000011.616923 4 40 00 00 01

Cheers,
Igor

---
drivers/hid/hid-a4tech.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/hid/hid-a4tech.c b/drivers/hid/hid-a4tech.c
index 9428ea7cdf8a..fafb9fa558e7 100644
--- a/drivers/hid/hid-a4tech.c
+++ b/drivers/hid/hid-a4tech.c
@@ -38,7 +38,7 @@ static int a4_input_mapped(struct hid_device *hdev, struct hid_input *hi,
{
struct a4tech_sc *a4 = hid_get_drvdata(hdev);

- if (usage->type == EV_REL && usage->code == REL_WHEEL)
+ if (usage->type == EV_REL && usage->code == REL_WHEEL_HI_RES)
set_bit(REL_HWHEEL, *bit);

if ((a4->quirks & A4_2WHEEL_MOUSE_HACK_7) && usage->hid == 0x00090007)
@@ -60,7 +60,7 @@ static int a4_event(struct hid_device *hdev, struct hid_field *field,
input = field->hidinput->input;

if (a4->quirks & A4_2WHEEL_MOUSE_HACK_B8) {
- if (usage->type == EV_REL && usage->code == REL_WHEEL) {
+ if (usage->type == EV_REL && usage->code == REL_WHEEL_HI_RES) {
a4->delayed_value = value;
return 1;
}
@@ -77,7 +77,7 @@ static int a4_event(struct hid_device *hdev, struct hid_field *field,
return 1;
}

- if (usage->code == REL_WHEEL && a4->hw_wheel) {
+ if (usage->code == REL_WHEEL_HI_RES && a4->hw_wheel) {
input_event(input, usage->type, REL_HWHEEL, value);
return 1;
}
--
2.21.0