[PATCH v3 1/3] HID: i2c-hid: Rely on HID descriptor fetch to probe

Kenny Levinsen
2024-04-26T22:57:57Z

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 internally
on a bus error and log. Treat the bus error as a missing device and
remove the error log so we can do away with the probe.

Tested-by: Lukasz Majczak <lma@chromium.org>
Reviewed-by: Lukasz Majczak <lma@chromium.org>
Signed-off-by: Kenny Levinsen <kl@kl.wtf>
---
drivers/hid/i2c-hid/i2c-hid-core.c | 21 ++++++---------------
1 file changed, 6 insertions(+), 15 deletions(-)

diff --git a/drivers/hid/i2c-hid/i2c-hid-core.c b/drivers/hid/i2c-hid/i2c-hid-core.c
index d965382196c6..6ffa43d245b4 100644
--- a/drivers/hid/i2c-hid/i2c-hid-core.c
+++ b/drivers/hid/i2c-hid/i2c-hid-core.c
@@ -872,12 +872,11 @@ 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;
- }
+
+ /* The i2c drivers are a bit inconsistent with their error
+ * codes, so treat everything as -ENXIO for now. */
+ if (error)
+ return -ENXIO;
}

/* Validate the length of HID descriptor, the 4 first bytes:
@@ -992,17 +991,9 @@ 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) {
- i2c_hid_dbg(ihid, "nothing at this address: %d\n", ret);
- return -ENXIO;
- }
-
ret = i2c_hid_fetch_hid_descriptor(ihid);
if (ret < 0) {
- dev_err(&client->dev,
- "Failed to fetch the HID Descriptor\n");
+ i2c_hid_dbg(ihid, "failed to fetch HID descriptor: %d\n", ret);
return ret;
}

--
2.44.0