Hi,
On Tue, Apr 23, 2024 at 5:26 AM Kenny Levinsen <kl@xxxxxx> wrote:
>
> To avoid error messages when a device is not present, b3a81b6c4fc6 added
> an initial bus probe using a dummy i2c_smbus_read_byte() call.
>
> Without this probe, i2c_hid_fetch_hid_descriptor() will fail with
> EREMOTEIO. Propagate the error up so the caller can handle EREMOTEIO
> gracefully, and remove the probe as it is no longer necessary.
>
> Signed-off-by: Kenny Levinsen <kl@xxxxxx>
> ---
> drivers/hid/i2c-hid/i2c-hid-core.c | 20 ++++++--------------
> 1 file changed, 6 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/hid/i2c-hid/i2c-hid-core.c b/drivers/hid/i2c-hid/i2c-hid-core.c
> index 2df1ab3c31cc..515a80dbf6c7 100644
> --- a/drivers/hid/i2c-hid/i2c-hid-core.c
> +++ b/drivers/hid/i2c-hid/i2c-hid-core.c
> @@ -894,12 +894,8 @@ static int i2c_hid_fetch_hid_descriptor(struct i2c_hid *ihid)
> ihid->wHIDDescRegister,
> &ihid->hdesc,
> sizeof(ihid->hdesc));
> - if (error) {
> - dev_err(&ihid->client->dev,
> - "failed to fetch HID descriptor: %d\n",
> - error);
> - return -ENODEV;
> - }
> + if (error)
> + return error;
> }
>
> /* Validate the length of HID descriptor, the 4 first bytes:
> @@ -1014,17 +1010,13 @@ static int __i2c_hid_core_probe(struct i2c_hid *ihid)
> struct hid_device *hid = ihid->hid;
> int ret;
>
> - /* Make sure there is something at this address */
> - ret = i2c_smbus_read_byte(client);
> - if (ret < 0) {
> + ret = i2c_hid_fetch_hid_descriptor(ihid);
> + if (ret == -EREMOTEIO) {
I worry a little bit about keying just off of -EREMOTEIO. If I'm
skimming the code properly it's up to the different i2c bus controller
to decide which error code to return here. Looking at, for instance,
"i2c-qcom-geni.c", I see:
[NACK] = {-ENXIO, "NACK: slv unresponsive, check its power/reset-ln"},
Maybe we should just use dev_dbg() in all cases here when we fail to
fetch the descriptor? ...otherwise I think some boards will start
getting a noisy error message.
...and confirmed that my skim seemed to be accurate. i put your
patches on my system and then changed the system to think my
hid-over-i2c device was at 0x11 instead of the normal 0x10. Now, I
get:
[ 5.973417] i2c_hid_of 4-0011: failed to fetch HID descriptor: -6
[ 5.979701] i2c_hid_of 4-0011: Power on failed: -6
-Doug
