Input: ili210x - probe even if no resolution information

Probe the touch controller driver even if resolution information is not
available. This can happen e.g. in case the touch controller suffered a
failed firmware update and is stuck in bootloader mode.

Signed-off-by: Marek Vasut <marex@denx.de>
Link: https://lore.kernel.org/r/20230217025200.203833-1-marex@denx.de
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/touchscreen/ili210x.c

@@ -370,22 +370,33 @@ static int ili251x_firmware_update_resolution(struct device *dev)
 
 	/* The firmware update blob might have changed the resolution. */
 	error = priv->chip->read_reg(client, REG_PANEL_INFO, &rs, sizeof(rs));
-	if (error)
-		return error;
+	if (!error) {
+		resx = le16_to_cpup((__le16 *)rs);
+		resy = le16_to_cpup((__le16 *)(rs + 2));
 
-	resx = le16_to_cpup((__le16 *)rs);
-	resy = le16_to_cpup((__le16 *)(rs + 2));
+		/* The value reported by the firmware is invalid. */
+		if (!resx || resx == 0xffff || !resy || resy == 0xffff)
+			error = -EINVAL;
+	}
 
-	/* The value reported by the firmware is invalid. */
-	if (!resx || resx == 0xffff || !resy || resy == 0xffff)
-		return -EINVAL;
+	/*
+	 * In case of error, the firmware might be stuck in bootloader mode,
+	 * e.g. after a failed firmware update. Set maximum resolution, but
+	 * do not fail to probe, so the user can re-trigger the firmware
+	 * update and recover the touch controller.
+	 */
+	if (error) {
+		dev_warn(dev, "Invalid resolution reported by controller.\n");
+		resx = 16384;
+		resy = 16384;
+	}
 
 	input_abs_set_max(priv->input, ABS_X, resx - 1);
 	input_abs_set_max(priv->input, ABS_Y, resy - 1);
 	input_abs_set_max(priv->input, ABS_MT_POSITION_X, resx - 1);
 	input_abs_set_max(priv->input, ABS_MT_POSITION_Y, resy - 1);
 
-	return 0;
+	return error;
 }
 
 static ssize_t ili251x_firmware_update_firmware_version(struct device *dev)
@@ -977,11 +988,10 @@ static int ili210x_i2c_probe(struct i2c_client *client)
 	if (priv->chip->has_pressure_reg)
 		input_set_abs_params(input, ABS_MT_PRESSURE, 0, 0xa, 0, 0);
 	error = ili251x_firmware_update_cached_state(dev);
-	if (error) {
-		dev_err(dev, "Unable to cache firmware information, err: %d\n",
-			error);
-		return error;
-	}
+	if (error)
+		dev_warn(dev, "Unable to cache firmware information, err: %d\n",
+			 error);
+
 	touchscreen_parse_properties(input, true, &priv->prop);
 
 	error = input_mt_init_slots(input, priv->chip->max_touches,