[PATCH] HID: i2c-hid: patch Lenovo Yoga Slim 7x Keyboard rdesc

[Lauri Tirkkonen <lauri@hacktheplanet.fi>]

The keyboard of this device has the following in its report description
for Usage (Keyboard) in Collection (Application):

	# 0x15, 0x00,                    //  Logical Minimum (0)                52
	# 0x25, 0x65,                    //  Logical Maximum (101)              54
	# 0x05, 0x07,                    //  Usage Page (Keyboard)              56
	# 0x19, 0x00,                    //  Usage Minimum (0)                  58
	# 0x29, 0xdd,                    //  Usage Maximum (221)                60
	# 0x81, 0x00,                    //  Input (Data,Arr,Abs)               62

Since the Usage Min/Max range exceeds the Logical Min/Max range,
keypresses outside the Logical range are not recognized. This includes,
for example, the Japanese language keyboard variant's keys for |, _ and
\.

Patch the report description to make the Logical range match the Usage
range, fixing the interpretation of keypresses above 101 on this device.

Signed-off-by: Lauri Tirkkonen <lauri@hacktheplanet.fi>
---
 drivers/hid/hid-ids.h              |  1 +
 drivers/hid/i2c-hid/i2c-hid-core.c | 25 +++++++++++++++++++++++++
 2 files changed, 26 insertions(+)

diff --git a/drivers/hid/hid-ids.h b/drivers/hid/hid-ids.h
index 5721b8414bbd..bbb932145d2c 100644
--- a/drivers/hid/hid-ids.h
+++ b/drivers/hid/hid-ids.h
@@ -715,6 +715,7 @@
 #define USB_DEVICE_ID_ITE_LENOVO_YOGA2  0x8350
 #define I2C_DEVICE_ID_ITE_LENOVO_LEGION_Y720	0x837a
 #define USB_DEVICE_ID_ITE_LENOVO_YOGA900	0x8396
+#define I2C_DEVICE_ID_ITE_LENOVO_YOGA_SLIM_7X	0x8987
 #define USB_DEVICE_ID_ITE8595		0x8595
 #define USB_DEVICE_ID_ITE_MEDION_E1239T	0xce50
 
diff --git a/drivers/hid/i2c-hid/i2c-hid-core.c b/drivers/hid/i2c-hid/i2c-hid-core.c
index 63f46a2e5788..d78bd97ec24e 100644
--- a/drivers/hid/i2c-hid/i2c-hid-core.c
+++ b/drivers/hid/i2c-hid/i2c-hid-core.c
@@ -740,6 +740,26 @@ static int i2c_hid_raw_request(struct hid_device *hid, unsigned char reportnum,
 	}
 }
 
+static void patch_lenovo_yoga_slim7x_keyboard_rdesc(struct i2c_hid *ihid,
+						    char *rdesc,
+						    unsigned int rsize)
+{
+	if (!(rsize == 0xb0 &&
+	      rdesc[0x34] == 0x15 && rdesc[0x35] == 0x00 && // Logical Minimum (0)
+	      rdesc[0x36] == 0x25 && rdesc[0x37] == 0x65 && // Logical Maximum (101)
+	      rdesc[0x38] == 0x05 && rdesc[0x39] == 0x07 && // Usage Page (Keyboard)
+	      rdesc[0x3a] == 0x19 && rdesc[0x3b] == 0x00 && // Usage Minimum (0)
+	      rdesc[0x3c] == 0x29 && rdesc[0x3d] == 0xdd))  // Usage Maximum (221)
+		return;
+
+	u8 logical_max = rdesc[0x37];
+	u8 usage_max = rdesc[0x3d];
+
+	rdesc[0x37] = usage_max;
+	i2c_hid_dbg(ihid, "%s: patched logical max from %u to %u\n", __func__,
+			logical_max, usage_max);
+}
+
 static int i2c_hid_parse(struct hid_device *hid)
 {
 	struct i2c_client *client = hid->driver_data;
@@ -793,6 +813,11 @@ static int i2c_hid_parse(struct hid_device *hid)
 		}
 	}
 
+	if (ihid->hid->vendor == USB_VENDOR_ID_ITE &&
+	    ihid->hid->product == I2C_DEVICE_ID_ITE_LENOVO_YOGA_SLIM_7X) {
+		patch_lenovo_yoga_slim7x_keyboard_rdesc(ihid, rdesc, rsize);
+	}
+
 	i2c_hid_dbg(ihid, "Report Descriptor: %*ph\n", rsize, rdesc);
 
 	ret = hid_parse_report(hid, rdesc, rsize);
-- 
2.51.0

-- 
Lauri Tirkkonen | lotheac @ IRCnet