[PATCH v12 09/14] HID: nintendo: patch hw version for userspace HID mappings

From: "Daniel J. Ogorchock" <djogorchock@gmail.com>
To: linux-input@vger.kernel.org
Cc: thunderbird2k@gmail.com, blaws05@gmail.com,
	benjamin.tissoires@redhat.com, jikos@kernel.org,
	Roderick.Colenbrander@sony.com, svv@google.com,
	s.jegen@gmail.com, carmueller@gmail.com,
	pgriffais@valvesoftware.com, hadess@hadess.net,
	"Daniel J. Ogorchock" <djogorchock@gmail.com>
Subject: [PATCH v12 09/14] HID: nintendo: patch hw version for userspace HID mappings
Date: Sat, 22 Aug 2020 23:41:52 -0500	[thread overview]
Message-ID: <20200823044157.339677-10-djogorchock@gmail.com> (raw)
In-Reply-To: <20200823044157.339677-1-djogorchock@gmail.com>

This patch sets the most significant bit of the hid hw version to allow
userspace to distinguish between this driver's input mappings vs. the
default hid mappings. This prevents breaking userspace applications that
use SDL2 for gamepad input, allowing them to distinguish the mappings
based on the version.

Signed-off-by: Daniel J. Ogorchock <djogorchock@gmail.com>
---
 drivers/hid/hid-nintendo.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/hid/hid-nintendo.c b/drivers/hid/hid-nintendo.c
index f2864fd9fc5d..c2f7dc83d875 100644
--- a/drivers/hid/hid-nintendo.c
+++ b/drivers/hid/hid-nintendo.c
@@ -1423,6 +1423,15 @@ static int nintendo_hid_probe(struct hid_device *hdev,
 		goto err_wq;
 	}
 
+	/*
+	 * Patch the hw version of pro controller/joycons, so applications can
+	 * distinguish between the default HID mappings and the mappings defined
+	 * by the Linux game controller spec. This is important for the SDL2
+	 * library, which has a game controller database, which uses device ids
+	 * in combination with version as a key.
+	 */
+	hdev->version |= 0x8000;
+
 	ret = hid_hw_start(hdev, HID_CONNECT_HIDRAW);
 	if (ret) {
 		hid_err(hdev, "HW start failed\n");
-- 
2.28.0

