Re: [PATCH 1/2] HID: logitech-hidpp: add HID++ 2.0 reprogrammable button support

[Elliot Douglas]

Thanks, that makes sense.

For Solaar, this is not continuously forced. The kernel only programs
temporary diversion when the device connects. Solaar can still issue HID++
commands through hidraw, so if Solaar changes reporting for the same controls
afterwards, the last writer wins.

If Solaar takes over those controls for custom actions, the kernel would stop
receiving the diverted button notifications for normal evdev reporting until
the kernel diverts the controls again, for example after reconnect. While the
controls remain diverted, hidraw clients should still receive the raw HID++
reports.

I have addressed the inline comments locally for v2:
- replaced the profile/count wrapper with NULL-terminated mapping arrays
- cached the selected mapping pointer in struct hidpp_device

I'll wait for Benjamin's input to send Patch v2.


On Wed, Jun 17, 2026 at 3:28 AM Bastien Nocera <hadess@xxxxxxxxxx> wrote:
>
> On Sat, 2026-06-13 at 10:51 -0700, Elliot Douglas wrote:
> > Some Logitech HID++ 2.0 mice can report diverted reprogrammable
> > controls through HID++ feature 0x1b04, SpecialKeysMseButtons /
> > REPROG_CONTROLS_V4, instead of the normal HID mouse report.
> >
> > Add a quirk-gated event path for those controls. The handler temporarily
> > diverts verified per-product controls, parses divertedButtonsEvent as the
> > current pressed-control list, and reports the corresponding evdev key state
> > for every mapped control.
> >
> > Keep the control mappings in per-product profiles so adding support for
> > another mouse does not change the evdev capabilities advertised by
> > already-supported devices.
>
> How does this forced setting work/clash with the programmable buttons
> in Solaar?
>
> I've added some inline comments below.
>
> >
> > Documentation for feature 0x1b04 describes divertedButtonsEvent as a list
> > of currently pressed diverted buttons, which is the event format handled
> > here.
> >
> > Link: https://lekensteyn.nl/files/logitech/x1b04_specialkeysmsebuttons.html
> >
> > Signed-off-by: Elliot Douglas <edouglas7358@xxxxxxxxx>
> > ---
> >  drivers/hid/hid-logitech-hidpp.c | 215 +++++++++++++++++++++++++++++++
> >  1 file changed, 215 insertions(+)
> >
> > diff --git a/drivers/hid/hid-logitech-hidpp.c b/drivers/hid/hid-logitech-hidpp.c
> > index 70ba1a5e40d8..24c9cfaa4f37 100644
> > --- a/drivers/hid/hid-logitech-hidpp.c
> > +++ b/drivers/hid/hid-logitech-hidpp.c
> > @@ -76,6 +76,7 @@ MODULE_PARM_DESC(disable_tap_to_click,
> >  #define HIDPP_QUIRK_HI_RES_SCROLL_1P0                BIT(28)
> >  #define HIDPP_QUIRK_WIRELESS_STATUS          BIT(29)
> >  #define HIDPP_QUIRK_RESET_HI_RES_SCROLL              BIT(30)
> > +#define HIDPP_QUIRK_HIDPP_REPROG_CONTROLS_BTNS       BIT(31)
> >
> >  /* These are just aliases for now */
> >  #define HIDPP_QUIRK_KBD_SCROLL_WHEEL HIDPP_QUIRK_HIDPP_WHEELS
> > @@ -205,6 +206,7 @@ struct hidpp_device {
> >       struct hidpp_scroll_counter vertical_wheel_counter;
> >
> >       u8 wireless_feature_index;
> > +     u8 reprog_controls_feature_index;
> >
> >       int hires_wheel_multiplier;
> >       u8 hires_wheel_feature_index;
> > @@ -3601,6 +3603,209 @@ static int hidpp10_extra_mouse_buttons_raw_event(struct hidpp_device *hidpp,
> >       return 1;
> >  }
> >
> > +/* -------------------------------------------------------------------------- */
> > +/* HID++2.0 reprogrammable controls                                           */
> > +/* -------------------------------------------------------------------------- */
> > +
> > +#define HIDPP_PAGE_REPROG_CONTROLS_V4                        0x1b04
> > +
> > +#define HIDPP_REPROG_CONTROLS_GET_COUNT                      0x00
> > +#define HIDPP_REPROG_CONTROLS_GET_CID_INFO           0x10
> > +#define HIDPP_REPROG_CONTROLS_SET_CONTROL_REPORTING  0x30
> > +
> > +#define HIDPP_REPROG_CONTROLS_FLAG_MOUSE             BIT(0)
> > +#define HIDPP_REPROG_CONTROLS_FLAG_DIVERT            BIT(5)
> > +
> > +#define HIDPP_REPROG_CONTROLS_TEMPORARY_DIVERTED     BIT(0)
> > +#define HIDPP_REPROG_CONTROLS_CHANGE_TEMPORARY_DIVERT        BIT(1)
> > +
> > +#define HIDPP_REPROG_CONTROLS_EVENT_DIVERTED         0x00
> > +
> > +struct hidpp_reprog_control_mapping {
> > +     u16 control;
> > +     u16 code;
> > +};
> > +
> > +struct hidpp_reprog_controls_profile {
> > +     const struct hidpp_reprog_control_mapping *mappings;
>
> probably needs a __counted_by(), or maybe as it's static, it might be
> better to not require an intermediate struct, and return a NULL-
> terminated array instead.
>
> > +     unsigned int mapping_count;
> > +};
> > +
> > +static const struct hidpp_reprog_controls_profile *
> > +hidpp20_reprog_controls_get_profile(struct hidpp_device *hidpp)
> > +{
> > +     return NULL;
> > +}
> > +
> > +static int hidpp20_reprog_controls_get_count(struct hidpp_device *hidpp)
> > +{
> > +     struct hidpp_report response;
> > +     u8 feature_index = hidpp->reprog_controls_feature_index;
> > +     u8 cmd = HIDPP_REPROG_CONTROLS_GET_COUNT;
> > +     int ret;
> > +
> > +     ret = hidpp_send_fap_command_sync(hidpp, feature_index, cmd, NULL, 0,
> > +                                       &response);
> > +     if (ret > 0)
> > +             return -EPROTO;
> > +     if (ret)
> > +             return ret;
> > +
> > +     return response.fap.params[0];
> > +}
> > +
> > +static int hidpp20_reprog_controls_get_cid_info(struct hidpp_device *hidpp,
> > +                                             u8 index, u16 *control,
> > +                                             u8 *flags)
> > +{
> > +     struct hidpp_report response;
> > +     u8 feature_index = hidpp->reprog_controls_feature_index;
> > +     u8 cmd = HIDPP_REPROG_CONTROLS_GET_CID_INFO;
> > +     int ret;
> > +
> > +     ret = hidpp_send_fap_command_sync(hidpp, feature_index, cmd, &index,
> > +                                       sizeof(index), &response);
> > +     if (ret > 0)
> > +             return -EPROTO;
> > +     if (ret)
> > +             return ret;
> > +
> > +     *control = get_unaligned_be16(&response.fap.params[0]);
> > +     *flags = response.fap.params[4];
> > +
> > +     return 0;
> > +}
> > +
> > +static bool hidpp20_reprog_controls_find_control(struct hidpp_device *hidpp,
> > +                                              u16 control)
> > +{
> > +     int count, ret;
> > +     u16 cid;
> > +     u8 flags;
> > +     int i;
> > +
> > +     count = hidpp20_reprog_controls_get_count(hidpp);
> > +     if (count < 0)
> > +             return false;
> > +
> > +     for (i = 0; i < count; i++) {
> > +             ret = hidpp20_reprog_controls_get_cid_info(hidpp, i, &cid,
> > +                                                        &flags);
> > +             if (ret)
> > +                     return false;
> > +
> > +             if (cid == control)
> > +                     return (flags & HIDPP_REPROG_CONTROLS_FLAG_MOUSE) &&
> > +                            (flags & HIDPP_REPROG_CONTROLS_FLAG_DIVERT);
> > +     }
> > +
> > +     return false;
> > +}
> > +
> > +static int hidpp20_reprog_controls_set_control_reporting(struct hidpp_device *hidpp,
> > +                                                      u16 control, u8 flags)
> > +{
> > +     struct hidpp_report response;
> > +     u8 params[5];
> > +
> > +     put_unaligned_be16(control, &params[0]);
> > +     params[2] = flags;
> > +     put_unaligned_be16(control, &params[3]);
> > +
> > +     return hidpp_send_fap_command_sync(hidpp,
> > +                                        hidpp->reprog_controls_feature_index,
> > +                                        HIDPP_REPROG_CONTROLS_SET_CONTROL_REPORTING,
> > +                                        params, sizeof(params), &response);
> > +}
> > +
> > +static void hidpp20_reprog_controls_connect(struct hidpp_device *hidpp)
> > +{
> > +     const struct hidpp_reprog_controls_profile *profile;
> > +     u8 flags = HIDPP_REPROG_CONTROLS_TEMPORARY_DIVERTED |
> > +                HIDPP_REPROG_CONTROLS_CHANGE_TEMPORARY_DIVERT;
> > +     unsigned int i;
> > +
> > +     if (!(hidpp->quirks & HIDPP_QUIRK_HIDPP_REPROG_CONTROLS_BTNS))
> > +             return;
> > +
> > +     profile = hidpp20_reprog_controls_get_profile(hidpp);
>
> Could the profile be cached in the hidpp_device struct?
>
> > +     if (!profile)
> > +             return;
> > +
> > +     if (hidpp_root_get_feature(hidpp, HIDPP_PAGE_REPROG_CONTROLS_V4,
> > +                                &hidpp->reprog_controls_feature_index))
> > +             return;
> > +
> > +     for (i = 0; i < profile->mapping_count; i++) {
> > +             u16 control = profile->mappings[i].control;
> > +
> > +             if (!hidpp20_reprog_controls_find_control(hidpp, control))
> > +                     continue;
> > +
> > +             hidpp20_reprog_controls_set_control_reporting(hidpp, control, flags);
> > +     }
> > +}
> > +
> > +static int hidpp20_reprog_controls_raw_event(struct hidpp_device *hidpp,
> > +                                          u8 *data, int size)
> > +{
> > +     const struct hidpp_reprog_controls_profile *profile;
> > +     const struct hidpp_reprog_control_mapping *mapping;
> > +     struct hidpp_report *report = (struct hidpp_report *)data;
> > +     u16 controls[4];
> > +     bool pressed;
> > +     unsigned int i, j;
> > +
> > +     if (!(hidpp->quirks & HIDPP_QUIRK_HIDPP_REPROG_CONTROLS_BTNS) ||
> > +         !hidpp->input ||
> > +         hidpp->reprog_controls_feature_index == 0xff)
> > +             return 0;
> > +
> > +     profile = hidpp20_reprog_controls_get_profile(hidpp);
> > +     if (!profile)
> > +             return 0;
> > +
> > +     if (size < HIDPP_REPORT_LONG_LENGTH ||
> > +         report->fap.feature_index != hidpp->reprog_controls_feature_index ||
> > +         report->fap.funcindex_clientid != HIDPP_REPROG_CONTROLS_EVENT_DIVERTED)
> > +             return 0;
> > +
> > +     for (i = 0; i < ARRAY_SIZE(controls); i++)
> > +             controls[i] = get_unaligned_be16(&report->fap.params[i * 2]);
> > +
> > +     for (i = 0; i < profile->mapping_count; i++) {
> > +             mapping = &profile->mappings[i];
> > +             pressed = false;
> > +
> > +             for (j = 0; j < ARRAY_SIZE(controls); j++) {
> > +                     if (controls[j] == mapping->control) {
> > +                             pressed = true;
> > +                             break;
> > +                     }
> > +             }
> > +
> > +             input_report_key(hidpp->input, mapping->code, pressed);
> > +     }
> > +
> > +     input_sync(hidpp->input);
> > +
> > +     return 1;
> > +}
> > +
> > +static void hidpp20_reprog_controls_populate_input(struct hidpp_device *hidpp,
> > +                                                struct input_dev *input_dev)
> > +{
> > +     const struct hidpp_reprog_controls_profile *profile;
> > +     unsigned int i;
> > +
> > +     profile = hidpp20_reprog_controls_get_profile(hidpp);
> > +     if (!profile)
> > +             return;
> > +
> > +     for (i = 0; i < profile->mapping_count; i++)
> > +             input_set_capability(input_dev, EV_KEY, profile->mappings[i].code);
> > +}
> > +
> >  static void hidpp10_extra_mouse_buttons_populate_input(
> >                       struct hidpp_device *hidpp, struct input_dev *input_dev)
> >  {
> > @@ -3859,6 +4064,9 @@ static void hidpp_populate_input(struct hidpp_device *hidpp,
> >
> >       if (hidpp->quirks & HIDPP_QUIRK_HIDPP_EXTRA_MOUSE_BTNS)
> >               hidpp10_extra_mouse_buttons_populate_input(hidpp, input);
> > +
> > +     if (hidpp->quirks & HIDPP_QUIRK_HIDPP_REPROG_CONTROLS_BTNS)
> > +             hidpp20_reprog_controls_populate_input(hidpp, input);
> >  }
> >
> >  static int hidpp_input_configured(struct hid_device *hdev,
> > @@ -3971,6 +4179,10 @@ static int hidpp_raw_hidpp_event(struct hidpp_device *hidpp, u8 *data,
> >                       return ret;
> >       }
> >
> > +     ret = hidpp20_reprog_controls_raw_event(hidpp, data, size);
> > +     if (ret != 0)
> > +             return ret;
> > +
> >       if (hidpp->quirks & HIDPP_QUIRK_HIDPP_CONSUMER_VENDOR_KEYS) {
> >               ret = hidpp10_consumer_keys_raw_event(hidpp, data, size);
> >               if (ret != 0)
> > @@ -4264,6 +4476,8 @@ static void hidpp_connect_event(struct work_struct *work)
> >                       return;
> >       }
> >
> > +     hidpp20_reprog_controls_connect(hidpp);
> > +
> >       if (hidpp->quirks & HIDPP_QUIRK_HIDPP_CONSUMER_VENDOR_KEYS) {
> >               ret = hidpp10_consumer_keys_connect(hidpp);
> >               if (ret)
> > @@ -4436,6 +4650,7 @@ static int hidpp_probe(struct hid_device *hdev, const struct hid_device_id *id)
> >       hidpp->hid_dev = hdev;
> >       hidpp->name = hdev->name;
> >       hidpp->quirks = id->driver_data;
> > +     hidpp->reprog_controls_feature_index = 0xff;
> >       hid_set_drvdata(hdev, hidpp);
> >
> >       ret = hid_parse(hdev);