linux-kernel - [PATCH v2] Bluetooth: btusb: add sysfs attribute to control USB alt setting

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Message-ID: <20241213120420.v2.1.Ifc708cc471a8834b344c26fce1ce2fe3e5992cad@changeid>
Date: Fri, 13 Dec 2024 12:04:22 +0800
From: Ying Hsu <yinghsu@...omium.org>
To: linux-bluetooth@...r.kernel.org,
	luiz.dentz@...il.com
Cc: chromeos-bluetooth-upstreaming@...omium.org,
	Ying Hsu <yinghsu@...omium.org>,
	Marcel Holtmann <marcel@...tmann.org>,
	linux-kernel@...r.kernel.org
Subject: [PATCH v2] Bluetooth: btusb: add sysfs attribute to control USB alt setting

When a Bluetooth raw socket is open, the HCI event related to SCO
connection changes are not dispatched to the hci_event module, and
the underlying Bluetooth controller's USB Interface 1 will not be
updated accordingly.

This patch adds `isoc_alt` sysfs attribute, allowing user space
to update the alternate setting of the USB interface alternate
setting as needed.

Signed-off-by: Ying Hsu <yinghsu@...omium.org>
---
This commit has been tested on a chromebook with AX211.

Changes in v2:
- Add check for the existence of a valid USB interface 1.

 drivers/bluetooth/btusb.c | 34 +++++++++++++++++++++++++++++++++-
 1 file changed, 33 insertions(+), 1 deletion(-)

diff --git a/drivers/bluetooth/btusb.c b/drivers/bluetooth/btusb.c
index 279fe6c115fa..7d7cfcd07aef 100644
--- a/drivers/bluetooth/btusb.c
+++ b/drivers/bluetooth/btusb.c
@@ -3645,6 +3645,32 @@ static const struct file_operations force_poll_sync_fops = {
 	.llseek		= default_llseek,
 };
 
+static ssize_t isoc_alt_show(struct device *dev,
+			     struct device_attribute *attr,
+			     char *buf)
+{
+	struct btusb_data *data = dev_get_drvdata(dev);
+
+	return sysfs_emit(buf, "%d\n", data->isoc_altsetting);
+}
+
+static ssize_t isoc_alt_store(struct device *dev,
+			      struct device_attribute *attr,
+			      const char *buf, size_t count)
+{
+	struct btusb_data *data = dev_get_drvdata(dev);
+	int alt;
+	int ret;
+
+	if (kstrtoint(buf, 10, &alt))
+		return -EINVAL;
+
+	ret = btusb_switch_alt_setting(data->hdev, alt);
+	return ret < 0 ? ret : count;
+}
+
+static DEVICE_ATTR_RW(isoc_alt);
+
 static int btusb_probe(struct usb_interface *intf,
 		       const struct usb_device_id *id)
 {
@@ -4008,6 +4034,10 @@ static int btusb_probe(struct usb_interface *intf,
 						 data->isoc, data);
 		if (err < 0)
 			goto out_free_dev;
+
+		err = device_create_file(&intf->dev, &dev_attr_isoc_alt);
+		if (err)
+			goto out_free_dev;
 	}
 
 	if (IS_ENABLED(CONFIG_BT_HCIBTUSB_BCM) && data->diag) {
@@ -4054,8 +4084,10 @@ static void btusb_disconnect(struct usb_interface *intf)
 	hdev = data->hdev;
 	usb_set_intfdata(data->intf, NULL);
 
-	if (data->isoc)
+	if (data->isoc) {
+		device_remove_file(&intf->dev, &dev_attr_isoc_alt);
 		usb_set_intfdata(data->isoc, NULL);
+	}
 
 	if (data->diag)
 		usb_set_intfdata(data->diag, NULL);
-- 
2.47.1.613.gc27f4b7a9f-goog