2018-05-09 19:12:56

by Dmitry Torokhov

Subject: [PATCH] HID: i2c-hid: check if device is there before really probing

From: Dmitry Torokhov <[email protected]>

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 <[email protected]>
---
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

2018-05-14 08:31:52

by Benjamin Tissoires

Subject: Re: [PATCH] HID: i2c-hid: check if device is there before really probing

On Wed, May 9, 2018 at 9:12 PM, Dmitry Torokhov <[email protected]> wrote:
> From: Dmitry Torokhov <[email protected]>
>
> 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 <[email protected]>
> ---

Looks good. Tested on a Dell XPS with an i2c-hid touchpad:
Reviewed-by: Benjamin Tissoires <[email protected]>

Cheers,
Benjamin

> 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
>

2018-05-15 09:17:04

by Jiri Kosina

Subject: Re: [PATCH] HID: i2c-hid: check if device is there before really probing

On Wed, 9 May 2018, Dmitry Torokhov wrote:

> From: Dmitry Torokhov <[email protected]>
>
> 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 <[email protected]>

Applied, thanks.

--
Jiri Kosina
SUSE Labs