Re: [PATCH v3] Input: elantech - fix x_max/y_max values

Since commit 37548659bb22 ("Input: elantech - query the min/max information beforehand too")
moved the querying of the x_max/y_max values from
elantech_set_input_params to elantech_query_info,
the returned x_max/y_max values are different than before,
at least for some firmware versions.

The reason is likely that this is now done before
elantech_set_absolute_mode does run.  So it may happen that
the returned values are exactly half of what they used to be,
which makes input_report_abs in PS/2 mode report ABS_X values which
exceed the x_max value, which is very annoying since the mouse stops
to move then, and ABS_Y value become negative, which is benign.

This was observed with a MSI GX70 laptop:

elantech: assuming hardware version 3 (with firmware version 0x250f01)
elantech: Synaptics capabilities query result 0x18, 0x17, 0x0b.
elantech: Elan sample query result 05, 0e, 00
input: ETPS/2 Elantech Touchpad as /devices/platform/i8042/serio...

This patch moves the code sending the ETP_FW_ID_QUERY command to
the function elantech_set_range and calls this function in
elantech_query_info for hw_version == 4, but for hw_version < 4 it is
called in elantech_setup_ps2 after the function elantech_set_absolute_mode.

It is right to switch the touchpad into absolute mode first to get valid
results from the ID query call in hardware version 2 and 3.

There is no way how this change can affect the state of the firmware
when elantech_setup_smbus is called later, since that can only happen for
hardware version 4, see elantech_init_smbusand elantech_use_host_notify
which uses ETP_NEW_IC_SMBUS_HOST_NOTIFY and info->bus.

The macro ETP_NEW_IC_SMBUS_HOST_NOTIFY can only return true
for (fw_version & 0x0f0000) == 0x0f0000 which implies v4 hardware.
The value info->bus can only be unequal to ETP_BUS_PS2_ONLY,
if elantech_get_resolution_v4 was called from elantech_query_info,
which is again guarded by info->hw_version == 4.

Fixes: 37548659bb22 ("Input: elantech - query the min/max information beforehand too")

Signed-off-by: Bernd Edlinger <redacted>
---
v3: Do the ID_QUEERY after set absoulute mode for hw_version < 4.
    Note: It turned out to be more difficult to call elantech_set_absolute_mode
    from elantech_query_info.

 drivers/input/mouse/elantech.c | 172 ++++++++++++++++++++++-------------------
 1 file changed, 94 insertions(+), 78 deletions(-)

diff --git a/drivers/input/mouse/elantech.c b/drivers/input/mouse/elantech.c
index 97381e2..5f4a1a4 100644
--- a/drivers/input/mouse/elantech.c
+++ b/drivers/input/mouse/elantech.c

@@ -1078,6 +1078,94 @@ static int elantech_set_absolute_mode(struct psmouse *psmouse)
 	return rc;
 }
 
+static int elantech_set_range(struct psmouse *psmouse,
+			      struct elantech_device_info *info)
+{
+	unsigned char param[3];
+	unsigned char traces;
+
+	/* query range information */
+	switch (info->hw_version) {
+	case 1:
+		info->x_min = ETP_XMIN_V1;
+		info->y_min = ETP_YMIN_V1;
+		info->x_max = ETP_XMAX_V1;
+		info->y_max = ETP_YMAX_V1;
+		break;
+
+	case 2:
+		if (info->fw_version == 0x020800 ||
+		    info->fw_version == 0x020b00 ||
+		    info->fw_version == 0x020030) {
+			info->x_min = ETP_XMIN_V2;
+			info->y_min = ETP_YMIN_V2;
+			info->x_max = ETP_XMAX_V2;
+			info->y_max = ETP_YMAX_V2;
+		} else {
+			int i;
+			int fixed_dpi;
+
+			i = (info->fw_version > 0x020800 &&
+			     info->fw_version < 0x020900) ? 1 : 2;
+
+			if (info->send_cmd(psmouse, ETP_FW_ID_QUERY, param))
+				return -EINVAL;
+
+			fixed_dpi = param[1] & 0x10;
+
+			if (((info->fw_version >> 16) == 0x14) && fixed_dpi) {
+				if (info->send_cmd(psmouse, ETP_SAMPLE_QUERY, param))
+					return -EINVAL;
+
+				info->x_max = (info->capabilities[1] - i) * param[1] / 2;
+				info->y_max = (info->capabilities[2] - i) * param[2] / 2;
+			} else if (info->fw_version == 0x040216) {
+				info->x_max = 819;
+				info->y_max = 405;
+			} else if (info->fw_version == 0x040219 || info->fw_version == 0x040215) {
+				info->x_max = 900;
+				info->y_max = 500;
+			} else {
+				info->x_max = (info->capabilities[1] - i) * 64;
+				info->y_max = (info->capabilities[2] - i) * 64;
+			}
+		}
+		break;
+
+	case 3:
+		if (info->send_cmd(psmouse, ETP_FW_ID_QUERY, param))
+			return -EINVAL;
+
+		info->x_max = (0x0f & param[0]) << 8 | param[1];
+		info->y_max = (0xf0 & param[0]) << 4 | param[2];
+		break;
+
+	case 4:
+		if (info->send_cmd(psmouse, ETP_FW_ID_QUERY, param))
+			return -EINVAL;
+
+		info->x_max = (0x0f & param[0]) << 8 | param[1];
+		info->y_max = (0xf0 & param[0]) << 4 | param[2];
+		traces = info->capabilities[1];
+		if ((traces < 2) || (traces > info->x_max))
+			return -EINVAL;
+
+		info->width = info->x_max / (traces - 1);
+
+		/* column number of traces */
+		info->x_traces = traces;
+
+		/* row number of traces */
+		traces = info->capabilities[2];
+		if ((traces >= 2) && (traces <= info->y_max))
+			info->y_traces = traces;
+
+		break;
+	}
+
+	return 0;
+}
+
 /*
  * (value from firmware) * 10 + 790 = dpi
  * we also have to convert dpi to dots/mm (*10/254 to avoid floating point)

@@ -1659,7 +1747,6 @@ static int elantech_query_info(struct psmouse *psmouse,
 			       struct elantech_device_info *info)
 {
 	unsigned char param[3];
-	unsigned char traces;
 	unsigned char ic_body[3];
 
 	memset(info, 0, sizeof(*info));

@@ -1759,85 +1846,9 @@ static int elantech_query_info(struct psmouse *psmouse,
 			psmouse_warn(psmouse,
 				     "failed to query resolution data.\n");
 		}
-	}
-
-	/* query range information */
-	switch (info->hw_version) {
-	case 1:
-		info->x_min = ETP_XMIN_V1;
-		info->y_min = ETP_YMIN_V1;
-		info->x_max = ETP_XMAX_V1;
-		info->y_max = ETP_YMAX_V1;
-		break;
-
-	case 2:
-		if (info->fw_version == 0x020800 ||
-		    info->fw_version == 0x020b00 ||
-		    info->fw_version == 0x020030) {
-			info->x_min = ETP_XMIN_V2;
-			info->y_min = ETP_YMIN_V2;
-			info->x_max = ETP_XMAX_V2;
-			info->y_max = ETP_YMAX_V2;
-		} else {
-			int i;
-			int fixed_dpi;
-
-			i = (info->fw_version > 0x020800 &&
-			     info->fw_version < 0x020900) ? 1 : 2;
-
-			if (info->send_cmd(psmouse, ETP_FW_ID_QUERY, param))
-				return -EINVAL;
 
-			fixed_dpi = param[1] & 0x10;
-
-			if (((info->fw_version >> 16) == 0x14) && fixed_dpi) {
-				if (info->send_cmd(psmouse, ETP_SAMPLE_QUERY, param))
-					return -EINVAL;
-
-				info->x_max = (info->capabilities[1] - i) * param[1] / 2;
-				info->y_max = (info->capabilities[2] - i) * param[2] / 2;
-			} else if (info->fw_version == 0x040216) {
-				info->x_max = 819;
-				info->y_max = 405;
-			} else if (info->fw_version == 0x040219 || info->fw_version == 0x040215) {
-				info->x_max = 900;
-				info->y_max = 500;
-			} else {
-				info->x_max = (info->capabilities[1] - i) * 64;
-				info->y_max = (info->capabilities[2] - i) * 64;
-			}
-		}
-		break;
-
-	case 3:
-		if (info->send_cmd(psmouse, ETP_FW_ID_QUERY, param))
-			return -EINVAL;
-
-		info->x_max = (0x0f & param[0]) << 8 | param[1];
-		info->y_max = (0xf0 & param[0]) << 4 | param[2];
-		break;
-
-	case 4:
-		if (info->send_cmd(psmouse, ETP_FW_ID_QUERY, param))
+		if (elantech_set_range(psmouse, info))
 			return -EINVAL;
-
-		info->x_max = (0x0f & param[0]) << 8 | param[1];
-		info->y_max = (0xf0 & param[0]) << 4 | param[2];
-		traces = info->capabilities[1];
-		if ((traces < 2) || (traces > info->x_max))
-			return -EINVAL;
-
-		info->width = info->x_max / (traces - 1);
-
-		/* column number of traces */
-		info->x_traces = traces;
-
-		/* row number of traces */
-		traces = info->capabilities[2];
-		if ((traces >= 2) && (traces <= info->y_max))
-			info->y_traces = traces;
-
-		break;
 	}
 
 	/* check for the middle button: DMI matching or new v4 firmwares */

@@ -2037,6 +2048,11 @@ static int elantech_setup_ps2(struct psmouse *psmouse,
 		goto init_fail;
 	}
 
+	if (info->hw_version < 4) {
+		if (elantech_set_range(psmouse, &etd->info))
+			goto init_fail;
+	}
+
 	if (info->fw_version == 0x381f17) {
 		etd->original_set_rate = psmouse->set_rate;
 		psmouse->set_rate = elantech_set_rate_restore_reg_07;