FAILED: patch "[PATCH] usb: typec: fsa4480: Check if the chip is really there" failed to apply to 6.6-stable tree

The patch below does not apply to the 6.6-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y
git checkout FETCH_HEAD
git cherry-pick -x e885f5f1f2b43575aa8e4e31404132d77d6663d1
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2024081202-author-suspense-c645@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^..

Possible dependencies:

e885f5f1f2b4 ("usb: typec: fsa4480: Check if the chip is really there") cf07c55f9922 ("usb: typec: fsa4480: Add support to swap SBU orientation")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From e885f5f1f2b43575aa8e4e31404132d77d6663d1 Mon Sep 17 00:00:00 2001
From: Konrad Dybcio <[email protected]>
Date: Mon, 29 Jul 2024 10:42:58 +0200
Subject: [PATCH] usb: typec: fsa4480: Check if the chip is really there

Currently, the driver will happily register the switch/mux devices, and so long as the i2c master doesn't complain, the user would never know there's something wrong.

Add a device id check (based on [1]) and return -ENODEV if the read fails or returns nonsense.

Checking the value on a Qualcomm SM6115P-based Lenovo Tab P11 tablet, the ID mentioned in the datasheet does indeed show up:
fsa4480 1-0042: Found FSA4480 v1.1 (Vendor ID = 0)

[1] https://www.onsemi.com/pdf/datasheet/fsa4480-d.pdf

index cb7cdf90cb0a..cd235339834b 100644
@@ -13,6 +13,10 @@
 #include <linux/usb/typec_dp.h>
 #include <linux/usb/typec_mux.h>
 
+#define FSA4480_DEVICE_ID	0x00
+ #define FSA4480_DEVICE_ID_VENDOR_ID	GENMASK(7, 6)
+ #define FSA4480_DEVICE_ID_VERSION_ID	GENMASK(5, 3)
+ #define FSA4480_DEVICE_ID_REV_ID	GENMASK(2, 0)
 #define FSA4480_SWITCH_ENABLE	0x04
 #define FSA4480_SWITCH_SELECT	0x05
 #define FSA4480_SWITCH_STATUS1	0x07

@@ -251,6 +255,7 @@ static int fsa4480_probe(struct i2c_client *client)
 	struct typec_switch_desc sw_desc = { };
 	struct typec_mux_desc mux_desc = { };
 	struct fsa4480 *fsa;
+	int val = 0;
 	int ret;
 
 	fsa = devm_kzalloc(dev, sizeof(*fsa), GFP_KERNEL);

@@ -268,6 +273,15 @@ static int fsa4480_probe(struct i2c_client *client)
 	if (IS_ERR(fsa->regmap))
 		return dev_err_probe(dev, PTR_ERR(fsa->regmap), "failed to initialize regmap\n");
 
+	ret = regmap_read(fsa->regmap, FSA4480_DEVICE_ID, &val);
+	if (ret || !val)
+		return dev_err_probe(dev, -ENODEV, "FSA4480 not found\n");
+
+	dev_dbg(dev, "Found FSA4480 v%lu.%lu (Vendor ID = %lu)\n",
+		FIELD_GET(FSA4480_DEVICE_ID_VERSION_ID, val),
+		FIELD_GET(FSA4480_DEVICE_ID_REV_ID, val),
+		FIELD_GET(FSA4480_DEVICE_ID_VENDOR_ID, val));
+
 	/* Safe mode */
 	fsa->cur_enable = FSA4480_ENABLE_DEVICE | FSA4480_ENABLE_USB;
 	fsa->mode = TYPEC_STATE_SAFE;