huion: Fail on parameter retrieval errors

Fail Huion tablet interface enabling and probing, if parameter retrieval
fails. Move the main code path out of the else block accordingly.

This should prevent devices appearing in a half-working state due to
original report descriptor being used, simplifying diagnostics. This
also makes it easier to add cleanup in later commits, as error handling
is simplified.

Author: spbnick

hid-huion.c

@@ -116,6 +116,10 @@ static int huion_tablet_enable(struct hid_device *hdev)
 	struct usb_device *usb_dev = hid_to_usb_dev(hdev);
 	struct huion_drvdata *drvdata = hid_get_drvdata(hdev);
 	__le16 buf[6];
+	s32 params[HUION_PH_ID_NUM];
+	s32 resolution;
+	__u8 *p;
+	s32 v;
 
 	/*
 	 * Read string descriptor containing tablet parameters. The specific
@@ -128,56 +132,54 @@ static int huion_tablet_enable(struct hid_device *hdev)
 				(USB_DT_STRING << 8) + 0x64,
 				0x0409, buf, sizeof(buf),
 				USB_CTRL_GET_TIMEOUT);
-	if (rc == -EPIPE)
-		hid_warn(hdev, "device parameters not found\n");
-	else if (rc < 0)
-		hid_warn(hdev, "failed to get device parameters: %d\n", rc);
-	else if (rc != sizeof(buf))
-		hid_warn(hdev, "invalid device parameters\n");
-	else {
-		s32 params[HUION_PH_ID_NUM];
-		s32 resolution;
-		__u8 *p;
-		s32 v;
+	if (rc == -EPIPE) {
+		hid_err(hdev, "device parameters not found\n");
+		return -ENODEV;
+	} else if (rc < 0) {
+		hid_err(hdev, "failed to get device parameters: %d\n", rc);
+		return -ENODEV;
+	} else if (rc != sizeof(buf)) {
+		hid_err(hdev, "invalid device parameters\n");
+		return -ENODEV;
+	}
 
-		/* Extract device parameters */
-		params[HUION_PH_ID_X_LM] = le16_to_cpu(buf[1]);
-		params[HUION_PH_ID_Y_LM] = le16_to_cpu(buf[2]);
-		params[HUION_PH_ID_PRESSURE_LM] = le16_to_cpu(buf[4]);
-		resolution = le16_to_cpu(buf[5]);
-		if (resolution == 0) {
-			params[HUION_PH_ID_X_PM] = 0;
-			params[HUION_PH_ID_Y_PM] = 0;
-		} else {
-			params[HUION_PH_ID_X_PM] = params[HUION_PH_ID_X_LM] *
-							1000 / resolution;
-			params[HUION_PH_ID_Y_PM] = params[HUION_PH_ID_Y_LM] *
-							1000 / resolution;
-		}
+	/* Extract device parameters */
+	params[HUION_PH_ID_X_LM] = le16_to_cpu(buf[1]);
+	params[HUION_PH_ID_Y_LM] = le16_to_cpu(buf[2]);
+	params[HUION_PH_ID_PRESSURE_LM] = le16_to_cpu(buf[4]);
+	resolution = le16_to_cpu(buf[5]);
+	if (resolution == 0) {
+		params[HUION_PH_ID_X_PM] = 0;
+		params[HUION_PH_ID_Y_PM] = 0;
+	} else {
+		params[HUION_PH_ID_X_PM] = params[HUION_PH_ID_X_LM] *
+						1000 / resolution;
+		params[HUION_PH_ID_Y_PM] = params[HUION_PH_ID_Y_LM] *
+						1000 / resolution;
+	}
 
-		/* Allocate fixed report descriptor */
-		drvdata->rdesc = devm_kmalloc(&hdev->dev,
-					sizeof(huion_tablet_rdesc_template),
-					GFP_KERNEL);
-		if (drvdata->rdesc == NULL) {
-			hid_err(hdev, "failed to allocate fixed rdesc\n");
-			return -ENOMEM;
-		}
-		drvdata->rsize = sizeof(huion_tablet_rdesc_template);
+	/* Allocate fixed report descriptor */
+	drvdata->rdesc = devm_kmalloc(&hdev->dev,
+				sizeof(huion_tablet_rdesc_template),
+				GFP_KERNEL);
+	if (drvdata->rdesc == NULL) {
+		hid_err(hdev, "failed to allocate fixed rdesc\n");
+		return -ENOMEM;
+	}
+	drvdata->rsize = sizeof(huion_tablet_rdesc_template);
 
-		/* Format fixed report descriptor */
-		memcpy(drvdata->rdesc, huion_tablet_rdesc_template,
-			drvdata->rsize);
-		for (p = drvdata->rdesc;
-		     p <= drvdata->rdesc + drvdata->rsize - 4;) {
-			if (p[0] == 0xFE && p[1] == 0xED && p[2] == 0x1D &&
-			    p[3] < sizeof(params)) {
-				v = params[p[3]];
-				put_unaligned(cpu_to_le32(v), (s32 *)p);
-				p += 4;
-			} else {
-				p++;
-			}
+	/* Format fixed report descriptor */
+	memcpy(drvdata->rdesc, huion_tablet_rdesc_template,
+		drvdata->rsize);
+	for (p = drvdata->rdesc;
+	     p <= drvdata->rdesc + drvdata->rsize - 4;) {
+		if (p[0] == 0xFE && p[1] == 0xED && p[2] == 0x1D &&
+		    p[3] < sizeof(params)) {
+			v = params[p[3]];
+			put_unaligned(cpu_to_le32(v), (s32 *)p);
+			p += 4;
+		} else {
+			p++;
 		}
 	}