git: ee46f649cb13 - stable/15 - ietp(4): Always overload HID report descriptor

The branch stable/15 has been updated by wulf:

URL: https://cgit.FreeBSD.org/src/commit/?id=ee46f649cb1344bdaf220b763efaad66d4c77491

commit ee46f649cb1344bdaf220b763efaad66d4c77491
Author:     Vladimir Kondratyev <wulf@FreeBSD.org>
AuthorDate: 2025-09-22 08:37:19 +0000
Commit:     Vladimir Kondratyev <wulf@FreeBSD.org>
CommitDate: 2025-09-29 21:51:36 +0000

    ietp(4): Always overload HID report descriptor
    
    It is required since "iichid(4): Always use wMaxInputLength bytes
    as input report length" commit.
    
    MFC after:      1 week
    
    (cherry picked from commit a9227954b0f01e950cc51d744af27585778ddf84)
---
 sys/dev/hid/ietp.c | 55 +++++++++++++++++++++++++++++++++++++++---------------
 1 file changed, 40 insertions(+), 15 deletions(-)

diff --git a/sys/dev/hid/ietp.c b/sys/dev/hid/ietp.c
index 73a5cb7414d4..a9d0295fb121 100644
--- a/sys/dev/hid/ietp.c
+++ b/sys/dev/hid/ietp.c
@@ -199,17 +199,32 @@ static const struct hid_device_id ietp_iic_devs[] = {
 	IETP_IIC_DEV("ELAN1000"),
 };
 
-static uint8_t const ietp_dummy_rdesc[] = {
+static uint8_t const ietp_dummy_rdesc_lo[] = {
 	0x05, HUP_GENERIC_DESKTOP,	/* Usage Page (Generic Desktop Ctrls)	*/
 	0x09, HUG_MOUSE,		/* Usage (Mouse)			*/
 	0xA1, 0x01,			/* Collection (Application)		*/
 	0x09, 0x01,			/*   Usage (0x01)			*/
+	0x15, 0x00,			/*   Logical Minimum (0)                */
+	0x26, 0xFF, 0x00,		/*   Logical Maximum (255)              */
 	0x95, IETP_REPORT_LEN_LO,	/*   Report Count (IETP_REPORT_LEN_LO)	*/
 	0x75, 0x08,			/*   Report Size (8)			*/
 	0x81, 0x02,			/*   Input (Data,Var,Abs)		*/
 	0xC0,				/* End Collection			*/
 };
 
+static uint8_t const ietp_dummy_rdesc_hi[] = {
+	0x05, HUP_GENERIC_DESKTOP,	/* Usage Page (Generic Desktop Ctrls)	*/
+	0x09, HUG_MOUSE,		/* Usage (Mouse)			*/
+	0xA1, 0x01,			/* Collection (Application)		*/
+	0x09, 0x01,			/*   Usage (0x01)			*/
+	0x15, 0x00,			/*   Logical Minimum (0)                */
+	0x26, 0xFF, 0x00,		/*   Logical Maximum (255)              */
+	0x95, IETP_REPORT_LEN_HI,	/*   Report Count (IETP_REPORT_LEN_HI)	*/
+	0x75, 0x08,			/*   Report Size (8)			*/
+	0x81, 0x02,			/*   Input (Data,Var,Abs)		*/
+	0xC0,				/* End Collection			*/
+};
+
 static const struct evdev_methods ietp_evdev_methods = {
 	.ev_open = &ietp_ev_open,
 	.ev_close = &ietp_ev_close,
@@ -433,28 +448,38 @@ ietp_res2dpmm(uint8_t res, bool hi_precision)
 static void
 ietp_iic_identify(driver_t *driver, device_t parent)
 {
-	void *d_ptr;
-	hid_size_t d_len;
-	int isize;
-	uint8_t iid;
+	device_t iichid = device_get_parent(parent);
+	static const uint16_t reg = IETP_PATTERN;
+	uint16_t addr = iicbus_get_addr(iichid) << 1;
+	uint8_t resp[2];
+	uint8_t cmd[2] = { reg & 0xff, (reg >> 8) & 0xff };
+	struct iic_msg msgs[2] = {
+	    { addr, IIC_M_WR | IIC_M_NOSTOP,  sizeof(cmd), cmd },
+	    { addr, IIC_M_RD, sizeof(resp), resp },
+	};
+	struct iic_rdwr_data ird = { msgs, nitems(msgs) };
+	uint8_t pattern;
 
 	if (HIDBUS_LOOKUP_ID(parent, ietp_iic_devs) == NULL)
 		return;
-	if (hid_get_report_descr(parent, &d_ptr, &d_len) != 0)
+
+	if (device_get_devclass(iichid) != devclass_find("iichid"))
 		return;
 
-	/*
-	 * Some Elantech trackpads have a mangled HID report descriptor, which
-	 * reads as having an incorrect input size (i.e. < IETP_REPORT_LEN_LO).
-	 * If the input size is incorrect, load a dummy report descriptor.
-	 */
+	DPRINTF("Read reg 0x%04x with size %zu\n", reg, sizeof(resp));
 
-	isize = hid_report_size_max(d_ptr, d_len, hid_input, &iid);
-	if (isize >= IETP_REPORT_LEN_LO)
+	if (hid_ioctl(parent, I2CRDWR, (uintptr_t)&ird) != 0)
 		return;
 
-	hid_set_report_descr(parent, ietp_dummy_rdesc,
-	    sizeof(ietp_dummy_rdesc));
+	DPRINTF("Response: %*D\n", (int)size(resp), resp, " ");
+
+	pattern = (resp[0] == 0xFF && resp[1] == 0xFF) ? 0 : resp[1];
+	if (pattern >= 0x02)
+		hid_set_report_descr(parent, ietp_dummy_rdesc_hi,
+		    sizeof(ietp_dummy_rdesc_hi));
+	else
+		hid_set_report_descr(parent, ietp_dummy_rdesc_lo,
+		    sizeof(ietp_dummy_rdesc_lo));
 }
 
 static int