[PATCH 2/3] HID: sony: Workaround for DS4 dongle hotplug kernel crash.

[Roderick Colenbrander <roderick@gaikai.com>]

From: Roderick Colenbrander <roderick.colenbrander@sony.com>

The hid-sony driver has custom DS4 connect/disconnect logic for the
DS4 dongle, which is a USB dongle acting as a proxy to Bluetooth
connected DS4.

The connect/disconnect logic works fine generally, however not in
conjunction with Steam. Steam implements its own DS4 driver using
hidraw. Both hid-sony and Steam are issuing their own HID requests
and are racing each other during DS4 dongle connect/disconnect
resulting in a kernel crash in hid-sony.

The problem is that upon a DS4 connect to the dongle, hid-sony kicks
of 'ds4_get_calibration_data' from within its dongle hotplug code.
The calibration code issues raw HID feature report for reportID 0x02.
When Steam is running, it issues a feature report for reportID 0x12
typically just prior to hid-sony requesting feature reportID 0x02.
The result is that 'ds4_get_calibration_data' receives the data Steam
requested as that's the HID report returing first. Currently this
results in it processing invalid data, which ultimately results in a
divide by zero upon a future 'dualshock4_parse_report'.

The solution for now is to check within 'ds4_get_calibration_data' to
check if we received data for the feature report we issued and if not
retry. This fixes bug 206785.

Signed-off-by: Roderick Colenbrander <roderick.colenbrander@sony.com>
---
 drivers/hid/hid-sony.c | 34 ++++++++++++++++++++++++++++------
 1 file changed, 28 insertions(+), 6 deletions(-)

diff --git a/drivers/hid/hid-sony.c b/drivers/hid/hid-sony.c
index 81d526a5d003..83a94ddbfa4e 100644
--- a/drivers/hid/hid-sony.c
+++ b/drivers/hid/hid-sony.c
@@ -1618,16 +1618,38 @@ static int dualshock4_get_calibration_data(struct sony_sc *sc)
 	 * of the controller, so that it sends input reports of type 0x11.
 	 */
 	if (sc->quirks & (DUALSHOCK4_CONTROLLER_USB | DUALSHOCK4_DONGLE)) {
+		int retries;
+
 		buf = kmalloc(DS4_FEATURE_REPORT_0x02_SIZE, GFP_KERNEL);
 		if (!buf)
 			return -ENOMEM;
 
-		ret = hid_hw_raw_request(sc->hdev, 0x02, buf,
-					 DS4_FEATURE_REPORT_0x02_SIZE,
-					 HID_FEATURE_REPORT,
-					 HID_REQ_GET_REPORT);
-		if (ret < 0)
-			goto err_stop;
+		/* We should normally receive the feature report data we asked
+		 * for, but hidraw applications such as Steam can issue feature
+		 * reports as well. In particular for Dongle reconnects, Steam
+		 * and this function are competing resulting in often receiving
+		 * data for a different HID report, so retry a few times.
+		 */
+		for (retries = 0; retries < 3; retries++) {
+			ret = hid_hw_raw_request(sc->hdev, 0x02, buf,
+						 DS4_FEATURE_REPORT_0x02_SIZE,
+						 HID_FEATURE_REPORT,
+						 HID_REQ_GET_REPORT);
+			if (ret < 0)
+				goto err_stop;
+
+			if (buf[0] != 0x02) {
+				if (retries < 2) {
+					hid_warn(sc->hdev, "Retrying DualShock 4 get calibration report (0x02) request\n");
+					continue;
+				} else {
+					ret = -EILSEQ;
+					goto err_stop;
+				}
+			} else {
+				break;
+			}
+		}
 	} else {
 		u8 bthdr = 0xA3;
 		u32 crc;
-- 
2.26.2