From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dmitry Torokhov Subject: [PATCH] HID: i2c-hid: check if device is there before really probing Date: Wed, 9 May 2018 12:12:15 -0700 Message-ID: <20180509191215.77406-1-dmitry.torokhov@gmail.com> Return-path: Sender: linux-kernel-owner@vger.kernel.org To: Jiri Kosina Cc: Benjamin Tissoires , linux-input@vger.kernel.org, linux-kernel@vger.kernel.org, Brian Norris , Douglas Anderson List-Id: linux-input@vger.kernel.org From: Dmitry Torokhov 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 --- drivers/hid/i2c-hid/i2c-hid.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/drivers/hid/i2c-hid/i2c-hid.c b/drivers/hid/i2c-hid/i2c-hid.c index 7230243b94d30..a59d483ff316a 100644 --- a/drivers/hid/i2c-hid/i2c-hid.c +++ b/drivers/hid/i2c-hid/i2c-hid.c @@ -1048,6 +1048,14 @@ 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; -- 2.17.0.441.gb46fe60e1d-goog