[PATCH v2 10/10] HID: steam: Retry send/recv reports if stale

[Vicki Pfau <vi@endrift.com>]

Sometimes recv report will reply with a stale result from a previous send
report. Instead of failing out, we should retry them, as they generally
reply correctly after three tries, give or take.

Signed-off-by: Vicki Pfau <vi@endrift.com>
---
 drivers/hid/hid-steam.c | 54 +++++++++++++++++++++++++++++++----------
 1 file changed, 41 insertions(+), 13 deletions(-)

diff --git a/drivers/hid/hid-steam.c b/drivers/hid/hid-steam.c
index 49f6733d8935..ba2dd40a7976 100644
--- a/drivers/hid/hid-steam.c
+++ b/drivers/hid/hid-steam.c
@@ -497,6 +497,43 @@ static int steam_write_settings(struct steam_device *steam,
 	return steam_recv_report(steam, cmd, 2 + cmd[1]);
 }
 
+static int steam_exchange_report(struct steam_device *steam, u8 *cmd, int csize,
+		u8 *reply, int rsize)
+{
+	unsigned int retries = 5;
+	int ret;
+
+	guard(mutex)(&steam->report_mutex);
+	do {
+		ret = steam_send_report(steam, cmd, csize);
+		if (ret < 0)
+			return ret;
+		ret = steam_recv_report(steam, reply, rsize);
+		/*
+		 * Sometimes this can fail on the first few tries on the Steam
+		 * Controller (2015). It appears to be a firmware bug, and Steam
+		 * itself just retries, so we should also retry a few times to
+		 * see if we get it.
+		 */
+		if (ret == -EPROTO)
+			continue;
+		if (ret < 0) {
+			hid_err(steam->hdev, "%s: error reading reply (%*ph)\n",
+					__func__, csize, cmd);
+			return ret;
+		}
+		if (reply[0] == cmd[0] && reply[1] >= 1)
+			break;
+		if (retries > 0)
+			continue;
+		hid_err(steam->hdev, "%s: invalid reply (%*ph)\n", __func__,
+				rsize, reply);
+		return -EPROTO;
+	} while (retries--);
+
+	return ret;
+}
+
 static int steam_get_serial(struct steam_device *steam)
 {
 	/*
@@ -507,15 +544,10 @@ static int steam_get_serial(struct steam_device *steam)
 	u8 cmd[] = {ID_GET_STRING_ATTRIBUTE, sizeof(steam->serial_no), ATTRIB_STR_UNIT_SERIAL};
 	u8 reply[3 + STEAM_SERIAL_LEN + 1];
 
-	guard(mutex)(&steam->report_mutex);
-	ret = steam_send_report(steam, cmd, sizeof(cmd));
+	ret = steam_exchange_report(steam, cmd, sizeof(cmd), reply, sizeof(reply));
 	if (ret < 0)
 		return ret;
-	ret = steam_recv_report(steam, reply, sizeof(reply));
-	if (ret < 0)
-		return ret;
-	if (reply[0] != ID_GET_STRING_ATTRIBUTE || reply[1] < 1 ||
-	    reply[1] > sizeof(steam->serial_no) || reply[2] != ATTRIB_STR_UNIT_SERIAL) {
+	if (reply[1] > sizeof(steam->serial_no) || reply[2] != ATTRIB_STR_UNIT_SERIAL) {
 		hid_err(steam->hdev, "%s: invalid reply (%*ph)\n", __func__,
 				(int)sizeof(reply), reply);
 		return -EIO;
@@ -534,14 +566,10 @@ static int steam_get_attributes(struct steam_device *steam)
 	int i;
 	struct steam_controller_attribute *attr;
 
-	guard(mutex)(&steam->report_mutex);
-	ret = steam_send_report(steam, cmd, sizeof(cmd));
-	if (ret < 0)
-		return ret;
-	ret = steam_recv_report(steam, reply, sizeof(reply));
+	ret = steam_exchange_report(steam, cmd, sizeof(cmd), reply, sizeof(reply));
 	if (ret < 0)
 		return ret;
-	if (reply[0] != ID_GET_ATTRIBUTES_VALUES || reply[1] < 2) {
+	if (reply[1] < 2) {
 		hid_err(steam->hdev, "%s: invalid reply (%*ph)\n", __func__,
 				(int)sizeof(reply), reply);
 		return -EIO;
-- 
2.54.0