Input: goodix - restore config on resume if necessary

Some devices, e.g the Trekstor Primetab S11B, lose there config over
a suspend/resume cycle (likely the controller loses power during suspend).

This commit reads back the config version on resume and if matches the
expected config version it resets the controller and resends the config
we read back and saved at probe time.

BugLink: https://bugzilla.redhat.com/show_bug.cgi?id=1786317
BugLink: https://github.com/nexus511/gpd-ubuntu-packages/issues/10
BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=199207Reviewed-by: Bastien Nocera <hadess@hadess.net>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20200307121505.3707-11-hdegoede@redhat.comSigned-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/touchscreen/goodix.c

@@ -1268,6 +1268,7 @@ static int __maybe_unused goodix_resume(struct device *dev)
 {
 	struct i2c_client *client = to_i2c_client(dev);
 	struct goodix_ts_data *ts = i2c_get_clientdata(client);
+	u8 config_ver;
 	int error;
 
 	if (ts->irq_pin_access_method == IRQ_PIN_ACCESS_NONE) {
@@ -1289,6 +1290,27 @@ static int __maybe_unused goodix_resume(struct device *dev)
 	if (error)
 		return error;
 
+	error = goodix_i2c_read(ts->client, ts->chip->config_addr,
+				&config_ver, 1);
+	if (error)
+		dev_warn(dev, "Error reading config version: %d, resetting controller\n",
+			 error);
+	else if (config_ver != ts->config[0])
+		dev_info(dev, "Config version mismatch %d != %d, resetting controller\n",
+			 config_ver, ts->config[0]);
+
+	if (error != 0 || config_ver != ts->config[0]) {
+		error = goodix_reset(ts);
+		if (error) {
+			dev_err(dev, "Controller reset failed.\n");
+			return error;
+		}
+
+		error = goodix_send_cfg(ts, ts->config, ts->chip->config_len);
+		if (error)
+			return error;
+	}
+
 	error = goodix_request_irq(ts);
 	if (error)
 		return error;