[ARCHIVED] Fix for CSR Dongle 0a12:0001 ID 0a12:0001 Cambridge Silicon Radio, Ltd Bluetooth Dongle (HCI mode)

archived.md

This gist is currenctly archived.

Please refer to previous revisions if you know what to do.

The patch proposed was merged into kernel in 5.8 release, but no longer working as of linux 5.11

I wonder if it's possible to rewrite and reflash the firmware of the CSR Clones. They could be an interesting thing for a common open-source firmware. The device is awful, but it's extremely common and cheap.

Chinese manufacturers produce identical looking Bluetooth dongles with different chips. They use new chips over time. So you can't have one firmware to fix them all.

Ah, that's unfortunate.

Not sure if this is mentioned or no since this gist is too long...
Plugging the cheap USB Bluetooth adapter in the USB 2.0 port was the fix for me (prev. was in USB 3.0 [the blue one])

Yes, that was also my biggest take home message
https://bugzilla.kernel.org/show_bug.cgi?id=60824#c167

Found this patch, but it's for a newer kernel:

--- a/net/bluetooth/hci_sync.c	2025-07-28 20:25:38.718355109 -0300
+++ b/net/bluetooth/hci_sync.c	2025-07-28 20:30:02.004160831 -0300
@@ -3960,8 +3960,6 @@
 	HCI_INIT(hci_write_inquiry_mode_sync),
 	/* HCI_OP_READ_INQ_RSP_TX_POWER */
 	HCI_INIT(hci_read_inq_rsp_tx_power_sync),
-	/* HCI_OP_READ_LOCAL_EXT_FEATURES */
-	HCI_INIT(hci_read_local_ext_features_1_sync),
 	/* HCI_OP_WRITE_AUTH_ENABLE */
 	HCI_INIT(hci_write_auth_enable_sync),
 	{}
@@ -4252,8 +4250,6 @@
 	HCI_INIT(hci_read_def_err_data_reporting_sync),
 	/* HCI_OP_READ_PAGE_SCAN_TYPE */
 	HCI_INIT(hci_read_page_scan_type_sync),
-	/* HCI_OP_READ_LOCAL_EXT_FEATURES */
-	HCI_INIT(hci_read_local_ext_features_all_sync),
 	{}
 };

There's no net/bluetooth/hci_sync.c in 5.15.

I made additional patch for 5.15, now all my adapters work more or less. Even with the other IDs, 33fa:0010, 33fa:0012 from UGREEN.

diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
index 7ed5d6e..0f16d88 100644
--- a/net/bluetooth/hci_core.c
+++ b/net/bluetooth/hci_core.c
@@ -482,6 +482,7 @@ static int hci_init2_req(struct hci_request *req, unsigned long opt)
 	if (lmp_inq_tx_pwr_capable(hdev))
 		hci_req_add(req, HCI_OP_READ_INQ_RSP_TX_POWER, 0, NULL);
 
+	if (0) // FIX
 	if (lmp_ext_feat_capable(hdev)) {
 		struct hci_cp_read_local_ext_features cp;
 
@@ -797,6 +798,7 @@ static int hci_init3_req(struct hci_request *req, unsigned long opt)
 	}
 
 	/* Read features beyond page 1 if available */
+	if (0) // FIX
 	for (p = 2; p < HCI_MAX_PAGES && p <= hdev->max_page; p++) {
 		struct hci_cp_read_local_ext_features cp;