HID: Add quirk for incorrect input length on Lenovo Y720

Apply it to the Lenovo Y720 gaming laptop I2C peripheral then.

This fixes dmesg being flooded with errors visible on un-suspend
in Linux Mint 19 Cinnamon.

Example of error log:

<...>
[    4.326588] i2c_hid i2c-ITE33D1:00: i2c_hid_get_input: incomplete report (2/4)
[    4.326845] i2c_hid i2c-ITE33D1:00: i2c_hid_get_input: incomplete report (2/4)
[    4.327095] i2c_hid i2c-ITE33D1:00: i2c_hid_get_input: incomplete report (2/4)
[    4.327341] i2c_hid i2c-ITE33D1:00: i2c_hid_get_input: incomplete report (2/4)
[    4.327609] i2c_hid i2c-ITE33D1:00: i2c_hid_get_input: incomplete report (2/4)
<...>

Example of fixed log (debug on)

<...>
[ 3731.333183] i2c_hid i2c-ITE33D1:00: input: 02 00
[ 3731.333581] i2c_hid i2c-ITE33D1:00: input: 02 00
[ 3731.333842] i2c_hid i2c-ITE33D1:00: input: 02 00
[ 3731.334107] i2c_hid i2c-ITE33D1:00: input: 02 00
[ 3731.334367] i2c_hid i2c-ITE33D1:00: input: 02 00
<...>

[jkosina@suse.cz: rebase onto more recent codebase]
Signed-off-by: Pavel Balan <admin@kryma.net>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

drivers/hid/hid-ids.h

@@ -631,6 +631,7 @@
 #define USB_VENDOR_ID_ITE               0x048d
 #define USB_DEVICE_ID_ITE_LENOVO_YOGA   0x8386
 #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 USB_DEVICE_ID_ITE8595		0x8595
 

drivers/hid/i2c-hid/i2c-hid-core.c

@@ -49,6 +49,8 @@
 #define I2C_HID_QUIRK_NO_IRQ_AFTER_RESET	BIT(1)
 #define I2C_HID_QUIRK_BOGUS_IRQ			BIT(4)
 #define I2C_HID_QUIRK_RESET_ON_RESUME		BIT(5)
+#define I2C_HID_QUIRK_BAD_INPUT_SIZE		BIT(6)
+
 
 /* flags */
 #define I2C_HID_STARTED		0
@@ -175,6 +177,8 @@ static const struct i2c_hid_quirks {
 		 I2C_HID_QUIRK_BOGUS_IRQ },
 	{ USB_VENDOR_ID_ALPS_JP, HID_ANY_ID,
 		 I2C_HID_QUIRK_RESET_ON_RESUME },
+	{ USB_VENDOR_ID_ITE, I2C_DEVICE_ID_ITE_LENOVO_LEGION_Y720,
+		I2C_HID_QUIRK_BAD_INPUT_SIZE },
 	{ 0, 0 }
 };
 
@@ -496,10 +500,16 @@ static void i2c_hid_get_input(struct i2c_hid *ihid)
 	}
 
 	if ((ret_size > size) || (ret_size < 2)) {
+		if (ihid->quirks & I2C_HID_QUIRK_BAD_INPUT_SIZE) {
+			ihid->inbuf[0] = size & 0xff;
+			ihid->inbuf[1] = size >> 8;
+			ret_size = size;
+		} else {
 			dev_err(&ihid->client->dev, "%s: incomplete report (%d/%d)\n",
 				__func__, size, ret_size);
 			return;
 		}
+	}
 
 	i2c_hid_dbg(ihid, "input: %*ph\n", ret_size, ihid->inbuf);