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Touchscreen support for the Samsung Galaxy Book4 Edge
On Fri, 22 May 2026 19:52:48 +0200,
Marcus Glocker <marcus@nazgul.ch> wrote:
>
> On Fri, May 22, 2026 at 01:04:29PM +0200, Kirill A. Korinsky wrote:
>
> > On Fri, 22 May 2026 05:52:43 +0200,
> > Marcus Glocker <marcus@nazgul.ch> wrote:
> > >
> > > On Fri, May 22, 2026 at 12:58:54AM +0200, Kirill A. Korinsky wrote:
> > >
> > > > On Thu, 21 May 2026 22:01:07 +0200,
> > > > Marcus Glocker <marcus@nazgul.ch> wrote:
> > > > >
> > > > > This diff enables touchscreen support for the Samsung Galaxy Book4
> > > > > Edge. For now we need to stick with polling since we can't figure
> > > > > out the GPIO pin for the touchscreen interrupts.
> > > > >
> > > > > In a summary, those are the changes we had to do in the different
> > > > > areas:
> > > > >
> > > > > - DTS: Power up the device and declare it on the I2C bus; no interrupt
> > > > > line, so it runs in polling mode (we can't determine the IRQ pin).
> > > > >
> > > > > - hidmt: Teach the shared multitouch layer to handle absolute
> > > > > touchscreens, not just touchpads.
> > > > >
> > > > > - imt: Recognize and claim the panel as a touchscreen so it's driven by
> > > > > the multitouch layer instead of being mistaken for a plain mouse.
> > > > >
> > > > > - ihidev: Synthesize the "finger lifted" event in polling mode, since
> > > > > the device signals release only by going silent.
> > > > >
> > > > > If you have an i2c-Precision touchpad or an i2c-HID keyboard, please
> > > > > test it still works.
> > > > >
> > > > > Please note that the diff doesn't introduce multi-finger gestures,
> > > > > just absolute pointer support (tap/drag).
> > > > >
> > > > > Otherwise, feedback, OKs?
> > > > >
> > > >
> > > > It brokes touchscreen on my honor.
> > >
> > > Could you send me a dmesg before and after the diff please?
> > >
> >
> > Sure, two dmesg attached, also here a diff.
> >
> > Keep in mind that multitouch works not each boot, and both boots was without
> > multitouch, and symptop of that: ihidev2: failed fetching report
> >
> > I had add some hacks which allows to have multitouch on touchpad, but it
> > seems not enough.
> >
> > Anyway, here a diff:
>
> Thanks for the report.
>
> It looks like your panel has a config report, while my hasn't, which
> has caused trying to switch the input mode where it shouldn't.
>
> Can you please try this updated diff? Your touchscreen should still
> attach to imt instead of ims, but hopefully works this time.
>
>
Doesn't work and I haven't see changes in dmesg.
> Index: sys/dev/hid/hidmt.c
> ===================================================================
> RCS file: /cvs/src/sys/dev/hid/hidmt.c,v
> diff -u -p -u -p -r1.16 hidmt.c
> --- sys/dev/hid/hidmt.c 21 Jul 2025 21:46:40 -0000 1.16
> +++ sys/dev/hid/hidmt.c 22 May 2026 17:18:37 -0000
> @@ -203,8 +203,10 @@ hidmt_setup(struct device *self, struct
> mt->sc_resy = hidmt_get_resolution(&h);
> }
> break;
> - case HID_USAGE2(HUP_DIGITIZERS, HUD_TIP_SWITCH):
> case HID_USAGE2(HUP_DIGITIZERS, HUD_CONFIDENCE):
> + mt->sc_flags |= HIDMT_HASCONFIDENCE;
> + /* FALLTHROUGH */
> + case HID_USAGE2(HUP_DIGITIZERS, HUD_TIP_SWITCH):
> case HID_USAGE2(HUP_DIGITIZERS, HUD_WIDTH):
> case HID_USAGE2(HUP_DIGITIZERS, HUD_HEIGHT):
> case HID_USAGE2(HUP_DIGITIZERS, HUD_CONTACTID):
> @@ -239,7 +241,17 @@ hidmt_setup(struct device *self, struct
> goto fail;
> }
>
> - if (hidmt_set_input_mode(mt, HIDMT_INPUT_MODE_MT_TOUCHPAD)) {
> + /* default touchscreen calibration to the device's reported range */
> + mt->sc_calibminx = mt->sc_minx;
> + mt->sc_calibmaxx = mt->sc_maxx;
> + mt->sc_calibminy = mt->sc_miny;
> + mt->sc_calibmaxy = mt->sc_maxy;
> + mt->sc_calibswapxy = 0;
> +
> + /* touchpads need switching into multitouch mode; touchscreens
> + * are already there and some mishandle the write, so skip it */
> + if (!(mt->sc_flags & HIDMT_TOUCHSCREEN) &&
> + hidmt_set_input_mode(mt, HIDMT_INPUT_MODE_MT_TOUCHPAD)) {
> printf("\n%s: switch to multitouch mode failed\n",
> self->dv_xname);
> goto fail;
> @@ -268,9 +280,14 @@ hidmt_configure(struct hidmt *mt)
> return;
>
> hw = wsmouse_get_hw(mt->sc_wsmousedev);
> - hw->type = WSMOUSE_TYPE_TOUCHPAD;
> - hw->hw_type = (mt->sc_clickpad
> - ? WSMOUSEHW_CLICKPAD : WSMOUSEHW_TOUCHPAD);
> + if (mt->sc_flags & HIDMT_TOUCHSCREEN) {
> + hw->type = WSMOUSE_TYPE_TPANEL;
> + hw->hw_type = WSMOUSEHW_TPANEL;
> + } else {
> + hw->type = WSMOUSE_TYPE_TOUCHPAD;
> + hw->hw_type = (mt->sc_clickpad
> + ? WSMOUSEHW_CLICKPAD : WSMOUSEHW_TOUCHPAD);
> + }
> hw->x_min = mt->sc_minx;
> hw->x_max = mt->sc_maxx;
> hw->y_min = mt->sc_miny;
> @@ -287,9 +304,13 @@ hidmt_attach(struct hidmt *mt, const str
> {
> struct wsmousedev_attach_args a;
>
> - printf(": %spad, %d contact%s\n",
> - (mt->sc_clickpad ? "click" : "touch"), mt->sc_num_contacts,
> - (mt->sc_num_contacts == 1 ? "" : "s"));
> + if (mt->sc_flags & HIDMT_TOUCHSCREEN)
> + printf(": touchscreen, %d contact%s\n", mt->sc_num_contacts,
> + (mt->sc_num_contacts == 1 ? "" : "s"));
> + else
> + printf(": %spad, %d contact%s\n",
> + (mt->sc_clickpad ? "click" : "touch"), mt->sc_num_contacts,
> + (mt->sc_num_contacts == 1 ? "" : "s"));
>
> a.accessops = ops;
> a.accesscookie = mt->sc_device;
> @@ -455,11 +476,30 @@ hidmt_input(struct hidmt *mt, uint8_t *d
> seencontacts++;
> }
>
> + /* no physical buttons on a touchscreen: a finger down is a click */
> + if (mt->sc_flags & HIDMT_TOUCHSCREEN)
> + buttons = tips ? 1 : 0;
> +
> s = spltty();
> if (mt->sc_buttons != buttons) {
> wsmouse_buttons(mt->sc_wsmousedev, buttons);
> mt->sc_buttons = buttons;
> }
> +
> + /* all fingers up: release exactly the slots we recorded as down */
> + if ((mt->sc_flags & HIDMT_TOUCHSCREEN) && tips == 0) {
> + for (i = 0; i < HIDMT_MAX_CONTACTS; i++) {
> + if (!(mt->sc_touches & (1 << i)))
> + continue;
> + mt->sc_contacts[i].seen = 0;
> + wsmouse_mtstate(mt->sc_wsmousedev, i, 0, 0, 0);
> + }
> + mt->sc_touches = 0;
> + wsmouse_input_sync(mt->sc_wsmousedev);
> + splx(s);
> + return;
> + }
> +
> for (i = 0; i < HIDMT_MAX_CONTACTS; i++) {
> if (!mt->sc_contacts[i].seen)
> continue;
> @@ -480,13 +520,19 @@ hidmt_input(struct hidmt *mt, uint8_t *d
> mt->sc_contacts[i].height,
> mt->sc_buttons));
>
> - if (mt->sc_contacts[i].tip && !mt->sc_contacts[i].confidence)
> + if ((mt->sc_flags & HIDMT_HASCONFIDENCE) &&
> + mt->sc_contacts[i].tip && !mt->sc_contacts[i].confidence)
> continue;
>
> /* Report width as pressure. */
> z = (mt->sc_contacts[i].tip
> ? imax(mt->sc_contacts[i].width, 50) : 0);
>
> + if (z > 0)
> + mt->sc_touches |= (1 << i);
> + else
> + mt->sc_touches &= ~(1 << i);
> +
> wsmouse_mtstate(mt->sc_wsmousedev,
> i, mt->sc_contacts[i].x, mt->sc_contacts[i].y, z);
> }
> @@ -520,12 +566,20 @@ hidmt_ioctl(struct hidmt *mt, u_long cmd
> break;
> }
>
> + case WSMOUSEIO_SCALIBCOORDS:
> + mt->sc_calibminx = wsmc->minx;
> + mt->sc_calibmaxx = wsmc->maxx;
> + mt->sc_calibminy = wsmc->miny;
> + mt->sc_calibmaxy = wsmc->maxy;
> + mt->sc_calibswapxy = wsmc->swapxy;
> + break;
> +
> case WSMOUSEIO_GCALIBCOORDS:
> - wsmc->minx = mt->sc_minx;
> - wsmc->maxx = mt->sc_maxx;
> - wsmc->miny = mt->sc_miny;
> - wsmc->maxy = mt->sc_maxy;
> - wsmc->swapxy = 0;
> + wsmc->minx = mt->sc_calibminx;
> + wsmc->maxx = mt->sc_calibmaxx;
> + wsmc->miny = mt->sc_calibminy;
> + wsmc->maxy = mt->sc_calibmaxy;
> + wsmc->swapxy = mt->sc_calibswapxy;
> wsmc->resx = mt->sc_resx;
> wsmc->resy = mt->sc_resy;
> break;
> @@ -593,4 +647,45 @@ hidmt_find_winptp_reports(const void *de
> nitems(cap_usages), cap_usages, ptp_collections);
>
> return (*input_rid > 0 && *config_rid > 0 && *cap_rid > 0);
> +}
> +
> +/* Like hidmt_find_winptp_reports() but for a HUD_TOUCHSCREEN: no
> + * Confidence usage, and the Input Mode config report is optional. */
> +int
> +hidmt_find_touchscreen_reports(const void *desc, int len, int *input_rid,
> + int *config_rid, int *cap_rid)
> +{
> + static int32_t ts_collections[] = {
> + HID_USAGE2(HUP_DIGITIZERS, HUD_FINGER), 0
> + };
> + static int32_t input_usages[] = {
> + /* report-level */
> + HID_USAGE2(HUP_DIGITIZERS, HUD_CONTACTCOUNT),
> + /* contact-level */
> + HID_USAGE2(HUP_GENERIC_DESKTOP, HUG_X),
> + HID_USAGE2(HUP_GENERIC_DESKTOP, HUG_Y),
> + HID_USAGE2(HUP_DIGITIZERS, HUD_TIP_SWITCH),
> + HID_USAGE2(HUP_DIGITIZERS, HUD_CONTACTID),
> + };
> + static int32_t cfg_usages[] = {
> + HID_USAGE2(HUP_DIGITIZERS, HUD_INPUT_MODE),
> + };
> + static int32_t cap_usages[] = {
> + HID_USAGE2(HUP_DIGITIZERS, HUD_CONTACT_MAX),
> + };
> +
> + *input_rid = hid_find_report(desc, len, hid_input,
> + HID_USAGE2(HUP_DIGITIZERS, HUD_TOUCHSCREEN),
> + nitems(input_usages), input_usages, ts_collections);
> + *cap_rid = hid_find_report(desc, len, hid_feature,
> + HID_USAGE2(HUP_DIGITIZERS, HUD_TOUCHSCREEN),
> + nitems(cap_usages), cap_usages, ts_collections);
> +
> + *config_rid = hid_find_report(desc, len, hid_feature,
> + HID_USAGE2(HUP_DIGITIZERS, HUD_CONFIG),
> + nitems(cfg_usages), cfg_usages, ts_collections);
> + if (*config_rid < 0)
> + *config_rid = 0;
> +
> + return (*input_rid > 0 && *cap_rid > 0);
> }
> Index: sys/dev/hid/hidmtvar.h
> ===================================================================
> RCS file: /cvs/src/sys/dev/hid/hidmtvar.h,v
> diff -u -p -u -p -r1.10 hidmtvar.h
> --- sys/dev/hid/hidmtvar.h 28 Oct 2025 15:36:46 -0000 1.10
> +++ sys/dev/hid/hidmtvar.h 22 May 2026 17:18:37 -0000
> @@ -36,7 +36,9 @@ struct hidmt_contact {
> struct hidmt {
> int sc_enabled;
> uint32_t sc_flags;
> -#define HIDMT_REVY 0x0001 /* Y-axis is reversed ("natural" scrolling) */
> +#define HIDMT_REVY 0x0001 /* Y-axis is reversed ("natural" scrolling) */
> +#define HIDMT_TOUCHSCREEN 0x0002 /* absolute touch panel, not a touchpad */
> +#define HIDMT_HASCONFIDENCE 0x0004 /* device reports a Confidence usage */
>
> struct device *sc_device;
> int (*hidev_report_type_conv)(int);
> @@ -61,9 +63,15 @@ struct hidmt {
> int sc_miny, sc_maxy;
> int sc_resx, sc_resy;
>
> + /* touchscreen calibration set via WSMOUSEIO_SCALIBCOORDS */
> + int sc_calibminx, sc_calibmaxx;
> + int sc_calibminy, sc_calibmaxy;
> + int sc_calibswapxy;
> +
> struct hidmt_contact sc_contacts[HIDMT_MAX_CONTACTS];
> int sc_cur_contactcount;
> int sc_buttons;
> + uint32_t sc_touches; /* bitmap of slots currently down */
> };
>
> int hidmt_set_input_mode(struct hidmt *, uint16_t);
> @@ -78,3 +86,4 @@ void hidmt_input(struct hidmt *, uint8_t
> int hidmt_ioctl(struct hidmt *, u_long, caddr_t, int, struct proc *);
> int hidmt_setup(struct device *, struct hidmt *, void *, int);
> int hidmt_find_winptp_reports(const void *, int, int *, int *, int *);
> +int hidmt_find_touchscreen_reports(const void *, int, int *, int *, int *);
> Index: sys/dev/i2c/ihidev.c
> ===================================================================
> RCS file: /cvs/src/sys/dev/i2c/ihidev.c,v
> diff -u -p -u -p -r1.41 ihidev.c
> --- sys/dev/i2c/ihidev.c 28 Oct 2025 15:36:46 -0000 1.41
> +++ sys/dev/i2c/ihidev.c 22 May 2026 17:18:37 -0000
> @@ -142,6 +142,7 @@ ihidev_attach(struct device *parent, str
> sc->sc_tag = ia->ia_tag;
> sc->sc_addr = ia->ia_addr;
> sc->sc_hid_desc_addr = ia->ia_size;
> + sc->sc_lastrepid = -1;
>
> if (ihidev_hid_command(sc, I2C_HID_CMD_DESCR, NULL) ||
> ihidev_hid_desc_parse(sc)) {
> @@ -159,10 +160,13 @@ ihidev_attach(struct device *parent, str
>
> /* find largest report size and allocate memory for input buffer */
> sc->sc_isize = letoh16(sc->hid_desc.wMaxInputLength);
> + sc->sc_repsizes = mallocarray(sc->sc_nrepid, sizeof(int),
> + M_DEVBUF, M_WAITOK | M_ZERO);
> for (repid = 0; repid < sc->sc_nrepid; repid++) {
> repsz = hid_report_size(sc->sc_report, sc->sc_reportlen,
> hid_input, repid);
> repsizes[repid] = repsz;
> + sc->sc_repsizes[repid] = repsz;
> if (repsz > sc->sc_isize)
> sc->sc_isize = repsz;
> if (repsz != 0)
> @@ -255,6 +259,9 @@ ihidev_detach(struct device *self, int f
> if (sc->sc_report != NULL)
> free(sc->sc_report, M_DEVBUF, sc->sc_reportlen);
>
> + if (sc->sc_repsizes != NULL)
> + free(sc->sc_repsizes, M_DEVBUF, sc->sc_nrepid * sizeof(int));
> +
> return (0);
> }
>
> @@ -718,10 +725,21 @@ ihidev_intr(void *arg)
> psize = sc->sc_ibuf[0] | sc->sc_ibuf[1] << 8;
> if (psize <= 2 || psize > sc->sc_isize) {
> if (sc->sc_poll) {
> - /*
> - * TODO: all fingers are up, should we pass to hid
> - * layer?
> - */
> + /* empty packet: hand the last subdev a zeroed report
> + * once so it releases its contacts (polled finger-up) */
> + int lrep = sc->sc_lastrepid;
> + int rsz;
> +
> + if (lrep >= 0 && lrep < sc->sc_nrepid &&
> + (scd = sc->sc_subdevs[lrep]) != NULL &&
> + (scd->sc_state & IHIDEV_OPEN) && !sc->sc_dying) {
> + rsz = sc->sc_repsizes[lrep];
> + if (rsz > 0 && rsz <= sc->sc_isize) {
> + memset(sc->sc_ibuf, 0, rsz);
> + scd->sc_intr(scd, sc->sc_ibuf, rsz);
> + }
> + sc->sc_lastrepid = -1;
> + }
> sc->sc_fastpoll = 0;
> goto more_polling;
> } else
> @@ -770,8 +788,10 @@ ihidev_intr(void *arg)
> return (1);
> }
>
> - if (!sc->sc_dying)
> + if (!sc->sc_dying) {
> + sc->sc_lastrepid = rep;
> scd->sc_intr(scd, p, psize);
> + }
>
> if (sc->sc_poll && (fast != sc->sc_fastpoll)) {
> DPRINTF(("%s: %s->%s polling\n", sc->sc_dev.dv_xname,
> Index: sys/dev/i2c/ihidev.h
> ===================================================================
> RCS file: /cvs/src/sys/dev/i2c/ihidev.h,v
> diff -u -p -u -p -r1.11 ihidev.h
> --- sys/dev/i2c/ihidev.h 7 Jan 2025 19:26:14 -0000 1.11
> +++ sys/dev/i2c/ihidev.h 22 May 2026 17:18:37 -0000
> @@ -85,6 +85,8 @@ struct ihidev_softc {
>
> u_int sc_isize;
> u_char *sc_ibuf;
> + int sc_lastrepid; /* report id of last non-empty input */
> + int *sc_repsizes; /* per-report input size, for poll path */
>
> int sc_refcnt;
>
> Index: sys/dev/i2c/imt.c
> ===================================================================
> RCS file: /cvs/src/sys/dev/i2c/imt.c,v
> diff -u -p -u -p -r1.7 imt.c
> --- sys/dev/i2c/imt.c 21 Jul 2025 21:46:40 -0000 1.7
> +++ sys/dev/i2c/imt.c 22 May 2026 17:18:37 -0000
> @@ -83,11 +83,15 @@ imt_match(struct device *parent, void *m
> if (iha->reportid == IHIDEV_CLAIM_MULTIPLEID) {
> ihidev_get_report_desc(iha->parent, &desc, &size);
> if (hidmt_find_winptp_reports(desc, size,
> + &input_rid, &conf_rid, &cap_rid) ||
> + hidmt_find_touchscreen_reports(desc, size,
> &input_rid, &conf_rid, &cap_rid)) {
> - iha->claims[0] = input_rid;
> - iha->claims[1] = conf_rid;
> - iha->claims[2] = cap_rid;
> - iha->nclaims = 3;
> + /* a touchscreen may have no config (Input Mode) report */
> + iha->nclaims = 0;
> + iha->claims[iha->nclaims++] = input_rid;
> + if (conf_rid > 0)
> + iha->claims[iha->nclaims++] = conf_rid;
> + iha->claims[iha->nclaims++] = cap_rid;
> return (IMATCH_DEVCLASS_DEVSUBCLASS);
> }
> }
> @@ -108,13 +112,18 @@ imt_attach(struct device *parent, struct
> sc->sc_hdev.sc_parent = iha->parent;
>
> ihidev_get_report_desc(iha->parent, &desc, &size);
> - hidmt_find_winptp_reports(desc, size, &sc->sc_rep_input,
> - &sc->sc_rep_config, &sc->sc_rep_cap);
>
> memset(mt, 0, sizeof(sc->sc_mt));
>
> - /* assume everything has "natural scrolling" where Y axis is reversed */
> - mt->sc_flags = HIDMT_REVY;
> + if (hidmt_find_winptp_reports(desc, size, &sc->sc_rep_input,
> + &sc->sc_rep_config, &sc->sc_rep_cap)) {
> + /* assume "natural scrolling" where the Y axis is reversed */
> + mt->sc_flags = HIDMT_REVY;
> + } else if (hidmt_find_touchscreen_reports(desc, size, &sc->sc_rep_input,
> + &sc->sc_rep_config, &sc->sc_rep_cap)) {
> + /* an absolute touch panel maps 1:1, so do not reverse Y */
> + mt->sc_flags = HIDMT_TOUCHSCREEN;
> + }
>
> mt->hidev_report_type_conv = ihidev_report_type_conv;
> mt->hidev_get_report = imt_hidev_get_report;
--
wbr, Kirill
Touchscreen support for the Samsung Galaxy Book4 Edge