Bt_coex support?

professor_jonny · May 11, 2025, 7:13pm

Hi I'm wondering on how to setup Bluetooth Coexistence and if it is possible under OpenWrt?

The device has a csr8811 HSI UART connected Bluetooth chip and it has a several GPIO attached to the GPIO of the IPQ8074.
The device has an ath11k chipset that supports bt_coex.

In the stock device the GPIO are labeled but not as the intended signal just labeled and defined as pta1_0, pta1_1, pta1_2, pta2_0, pta2_1 and pta2_2 so it is not real apparent what the gpio is.
Is there a way to determine this and is there a device setup with this configured so I may look at the dts?

I know the terminals are for PTA (Packet Traffic Arbitration), is there software to look at the firmware of the module and determine the pinout as I have a dump of the firmware?

WLAN_ACTIVE - signals when an 802.11 device is active, 802.11–>BT
BT_PRIORITY - categorizes the Bluetooth signal, BT–>802.11
BT_STATE -  signals the presence of a Bluetooth transmission.

sfx2000 · May 12, 2025, 12:52am

Quick question - are you looking to use the BT interface, or just ensure it's not getting in the way of 2.4GHz wifi?

professor_jonny · May 12, 2025, 2:32am

I was not really planning anything more just looking to support what best I can the oem functions in porting this device to vanilla OpenWrt.
I'm sort of using it to tinker and learn, but to be honest I'm really unsure of a relevant purpose for Bluetooth on a router, I'm sort of lost as in a use case for it?

I guess If the Bluetooth module can detect the presence of Bluetooth in use and disable the overlapping channels of WI-FI that would be great I guess, I don't know is that a possibility?

The interesting thing is the router does have a speaker so in theory it could be used for Bluetooth speaker if you really did not care for sound quality.

sfx2000 · May 12, 2025, 3:48am

Things don't work that way - BT is it's thing, and Wifi is another from an AP perspective...

professor_jonny · May 12, 2025, 4:30am

It does look like the Bluetooth is just used in the factory software to configure the device to atatch to the correct WI-FI network from an apple device.
Setup is done over Wi-Fi.

I don't know if there is any other feature outside of that but there is a mac address assigned to it in the app.

professor_jonny · May 13, 2025, 4:39am

I looked through the /torvalds/linux driver source and it seems there is little to nothing in the ath 10k and 11k regarding bx_coex it seems ath9k has all the dps properties for 2 and 3 wire bt_coex.
i read a bit and it seems ath10 and 11k do some sort of digital or serial channel, and it is behind the great Qualcomm firewall.

github.com/torvalds/linux

drivers/net/wireless/ath/ath9k/btcoex.h

e9565e23c

/*
 * Copyright (c) 2009-2011 Atheros Communications Inc.
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#ifndef BTCOEX_H
#define BTCOEX_H

#include "hw.h"

This file has been truncated. show original

linux/drivers/net/wireless/ath/ath9k/btcoex.c at e9565e23cd89d4d5cd4388f8742130be1d6f182d · torvalds/linux

sfx2000 · May 13, 2025, 11:36pm

Yeah - QSDK and the closed sourced drivers have some of this, and keep in mind that the driver does have to coordinate with both devices - should note that CSR is owned by Qualcomm - one of many companies they've acquired over the years...

professor_jonny · May 14, 2025, 7:51pm

It looks like coex is over WMI in ath11k
linux/drivers/net/wireless/ath/ath11k/wmi.h at master · torvalds/linux

In ath10k there is still gpio but it is not apparent what is what and how it works (lack of documentation and naming of gpio).

WMI_10_2_COEX_GPIO
WMI_10_2_RX_BATCH_MODE = BIT(0),
WMI_10_2_ATF_CONFIG = BIT(1),
WMI_10_2_COEX_GPIO = BIT(3),

github.com/torvalds/linux

drivers/net/wireless/ath/ath10k/wmi.c

master


      
          		return ERR_PTR(-ENOMEM);
          
          	if (test_bit(WMI_SERVICE_TDLS_UAPSD_SLEEP_STA, ar->wmi.svc_map))
          		num_tdls_sleep_sta = TARGET_10_4_NUM_TDLS_SLEEP_STA;
          
          	cmd = (struct wmi_ext_resource_config_10_4_cmd *)skb->data;
          	cmd->host_platform_config = __cpu_to_le32(type);
          	cmd->fw_feature_bitmap = __cpu_to_le32(fw_feature_bitmap);
          	cmd->wlan_gpio_priority = __cpu_to_le32(ar->coex_gpio_pin);
          	cmd->coex_version = __cpu_to_le32(WMI_NO_COEX_VERSION_SUPPORT);
          	cmd->coex_gpio_pin1 = __cpu_to_le32(-1);
          	cmd->coex_gpio_pin2 = __cpu_to_le32(-1);
          	cmd->coex_gpio_pin3 = __cpu_to_le32(-1);
          	cmd->num_tdls_vdevs = __cpu_to_le32(TARGET_10_4_NUM_TDLS_VDEVS);
          	cmd->num_tdls_conn_table_entries = __cpu_to_le32(20);
          	cmd->max_tdls_concurrent_sleep_sta = __cpu_to_le32(num_tdls_sleep_sta);
          	cmd->max_tdls_concurrent_buffer_sta =
          			__cpu_to_le32(TARGET_10_4_NUM_TDLS_BUFFER_STA);
          
          	ath10k_dbg(ar, ATH10K_DBG_WMI,
          		   "wmi ext resource config host type %d firmware feature bitmap %08x\n",

A-Somebody_8272 · May 15, 2025, 6:27pm

I’m really unsure if we are gonna get LCD, Bluetooth and Speaker to work in OpenWRT…. The speaker is connected directly to the LCD module anyway as you know, the LCD even has an vibration motor and is touch capable if you didn’t already know i don’t know for which purpose it will be useful:thinking:

We need to get the cooling Fan working first I guess as it gets very hot👍 and LED ring at the bottom base is always at full brightness which will get annoying after a while.