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

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

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@JeffreyO Thanks a lot for going above and beyond with your teardown! I remember trying to find the actual Chinese ASIC vendor, which (unless one takes a microscope photo of the bare die) it's going to be hard, but there are mentions to companies like Barrot in the kernel, which may be a good start point for more shady stuff:

If someone tried to clone the CSR chips they haven't done it correctly. ¯_(ツ)_/¯

Thank you. Also, for anyone wondering, there is a way to properly and nondestructively open up the USB dongle. I just gently pried it apart and wiggled it enough and was lucky not to break anything.
But, that's not the right way. The right way is that there's a clip in the USB part latching to the outside of the case. You press down on that and slide the dongle apart away from the metal. It should all come out in one piece.

To put it back together, you sandwich the plastic parts and the PCB back together and slide it into the metal part (Keep it mind that those 2 tiny divots in the metal are the clips. It only goes together one way.) while applying very light pressure to the clip. You should hear a click when everything is back together successfully.

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icaroerasmo commented Dec 13, 2023

This patch helped get the Ritmix RWA-350 working on Ubuntu 22.04.
Shown in lsusb as:
ID 0a12:0001 Cambridge Silicon Radio, Ltd Bluetooth Dongle (HCI mode)
I cleaned up the patch:

diff --git a/drivers/bluetooth/btusb.c b/drivers/bluetooth/btusb.c
index 8c41c76..9632251 100644
--- a/drivers/bluetooth/btusb.c
+++ b/drivers/bluetooth/btusb.c
@@ -1979,6 +1979,8 @@ static int btusb_setup_csr(struct hci_dev *hdev)
 		set_bit(HCI_QUIRK_BROKEN_STORED_LINK_KEY, &hdev->quirks);
 		set_bit(HCI_QUIRK_BROKEN_ERR_DATA_REPORTING, &hdev->quirks);
+		set_bit(HCI_QUIRK_BROKEN_FILTER_CLEAR_ALL, &hdev->quirks);
+		set_bit(HCI_QUIRK_NO_SUSPEND_NOTIFIER, &hdev->quirks);
 		/* Clear the reset quirk since this is not an actual
 		 * early Bluetooth 1.1 device from CSR.
@@ -2018,7 +2020,7 @@ static int btusb_setup_csr(struct hci_dev *hdev)
 		if (ret >= 0)
-			bt_dev_err(hdev, "CSR: Failed to suspend the device for our Barrot 8041a02 receive-issue workaround");
+			bt_dev_warn(hdev, "CSR: Couldn't suspend the device for our Barrot 8041a02 receive-issue workaround");
diff --git a/include/net/bluetooth/hci.h b/include/net/bluetooth/hci.h
index 9ce46cb..b97602a 100644
--- a/include/net/bluetooth/hci.h
+++ b/include/net/bluetooth/hci.h
@@ -255,6 +255,7 @@ enum {
 	 * during the hdev->setup vendor callback.
 /* HCI device flags */
diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
index bb84ff5..2a7af9a 100644
--- a/net/bluetooth/hci_core.c
+++ b/net/bluetooth/hci_core.c
@@ -294,6 +294,7 @@ static void bredr_setup(struct hci_request *req)
 	/* Clear Event Filters */
 	flt_type = HCI_FLT_CLEAR_ALL;
+	if (!test_bit(HCI_QUIRK_BROKEN_FILTER_CLEAR_ALL, &req->hdev->quirks))
 	hci_req_add(req, HCI_OP_SET_EVENT_FLT, 1, &flt_type);
 	/* Connection accept timeout ~20 secs */
diff --git a/net/bluetooth/hci_request.c b/net/bluetooth/hci_request.c
index c2db60a..39a871a 100644
--- a/net/bluetooth/hci_request.c
+++ b/net/bluetooth/hci_request.c
@@ -1160,6 +1160,9 @@ static void hci_req_clear_event_filter(struct hci_request *req)
 	if (!hci_dev_test_flag(req->hdev, HCI_BREDR_ENABLED))
+	if (test_bit(HCI_QUIRK_BROKEN_FILTER_CLEAR_ALL, &req->hdev->quirks))
+		return;
 	if (hci_dev_test_flag(req->hdev, HCI_EVENT_FILTER_CONFIGURED)) {
 		memset(&f, 0, sizeof(f));
 		f.flt_type = HCI_FLT_CLEAR_ALL;
@@ -1178,6 +1181,9 @@ static void hci_req_set_event_filter(struct hci_request *req)
 	if (!hci_dev_test_flag(hdev, HCI_BREDR_ENABLED))
+	if (test_bit(HCI_QUIRK_BROKEN_FILTER_CLEAR_ALL, &hdev->quirks))
+		return;
 	/* Always clear event filter when starting */

Extract the linux-source archive corresponding to your kernel and do the following:

$ patch -p1 < csr-clean.patch
$ make -C /lib/modules/$(uname -r)/build M=$(pwd)/net/bluetooth ccflags-y="$(echo "-include "$(pwd)/include/net/bluetooth/{bluetooth.h,hci.h})" modules
$ make -C /lib/modules/$(uname -r)/build M=$(pwd)/drivers/bluetooth ccflags-y="$(echo "-include "$(pwd)/include/net/bluetooth/{bluetooth.h,hci.h})" modules
$ strip --strip-debug net/bluetooth/bluetooth.ko
$ strip --strip-debug drivers/bluetooth/btusb.ko

Then you can replace the old drivers in /usr/lib/modules/$(uname -r)/kernel with the new ones. Don't forget to backup the old files.

It worked for me, tanks.

I currently have kernel 5.15.0-78-generic

My archives copilled:

I backed up and replaced the files

btusb.ko in /usr/lib/modules/5.15.0-XX-generic/kernel/drivers/bluetooth bluetooth.ko in /usr/lib/modules/5.15.0-XX-generic/kernel/net/bluetooth/

I have no idea on how to apply those patches and I'm willing a lot do so as my usb dongle shows up with same name in lsusb. Is there any material or could you explain me in a simple manner so I can reproduce it myself for kernel 6.6.6-arch1-1?

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