linux-kernel - [PATCH v2 1/3] HID: i2c-hid: Rely on HID descriptor fetch to probe

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Message-ID: <20240423122518.34811-2-kl@kl.wtf>
Date: Tue, 23 Apr 2024 14:07:53 +0200
From: Kenny Levinsen <kl@...wtf>
To: Jiri Kosina <jikos@...nel.org>,
	Dmitry Torokhov <dtor@...omium.org>,
	Benjamin Tissoires <benjamin.tissoires@...hat.com>,
	Douglas Anderson <dianders@...omium.org>,
	Hans de Goede <hdegoede@...hat.com>,
	Maxime Ripard <mripard@...nel.org>,
	Kai-Heng Feng <kai.heng.feng@...onical.com>,
	Johan Hovold <johan+linaro@...nel.org>,
	linux-input@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Radoslaw Biernacki <rad@...omium.org>,
	Lukasz Majczak <lma@...omium.org>
Cc: Kenny Levinsen <kl@...wtf>
Subject: [PATCH v2 1/3] HID: i2c-hid: Rely on HID descriptor fetch to probe

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@...wtf>
---
 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) {
 		i2c_hid_dbg(ihid, "nothing at this address: %d\n", ret);
 		return -ENXIO;
-	}
-
-	ret = i2c_hid_fetch_hid_descriptor(ihid);
-	if (ret < 0) {
+	} else if (ret < 0) {
 		dev_err(&client->dev,
-			"Failed to fetch the HID Descriptor\n");
+			"failed to fetch HID descriptor: %d\n", ret);
 		return ret;
 	}
 
-- 
2.44.0