From: Dmitry Torokhov Date: Wed, 9 May 2018 19:12:15 +0000 (-0700) Subject: HID: i2c-hid: check if device is there before really probing X-Git-Url: http://git.cdn.openwrt.org/?a=commitdiff_plain;h=b3a81b6c4fc6730ac49e20d789a93c0faabafc98;p=openwrt%2Fstaging%2Fblogic.git HID: i2c-hid: check if device is there before really probing On many Chromebooks touch devices are multi-sourced; the components are electrically compatible and one can be freely swapped for another without changing the OS image or firmware. To avoid bunch of scary messages when device is not actually present in the system let's try testing basic communication with it and if there is no response terminate probe early with -ENXIO. Signed-off-by: Dmitry Torokhov Reviewed-by: Benjamin Tissoires Signed-off-by: Jiri Kosina --- diff --git a/drivers/hid/i2c-hid/i2c-hid.c b/drivers/hid/i2c-hid/i2c-hid.c index cf71c33ac2b2..c5ad918e36e3 100644 --- a/drivers/hid/i2c-hid/i2c-hid.c +++ b/drivers/hid/i2c-hid/i2c-hid.c @@ -1060,6 +1060,14 @@ static int i2c_hid_probe(struct i2c_client *client, pm_runtime_enable(&client->dev); device_enable_async_suspend(&client->dev); + /* Make sure there is something at this address */ + ret = i2c_smbus_read_byte(client); + if (ret < 0) { + dev_dbg(&client->dev, "nothing at this address: %d\n", ret); + ret = -ENXIO; + goto err_pm; + } + ret = i2c_hid_fetch_hid_descriptor(ihid); if (ret < 0) goto err_pm;