Received-SPF: pass (google.com: best guess record for domain of linux-bluetooth-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
From:   Christian Hewitt <christianshewitt@gmail.com>
Content-Type: text/plain;
        charset=utf-8
Content-Transfer-Encoding: quoted-printable
Mime-Version: 1.0 (Mac OS X Mail 12.4 \(3445.104.14\))
Subject: How to handle different operating speed for QCA9377 SDIO BT module?
Message-Id: <1D4C533D-575D-4AC5-A627-389502097A77@gmail.com>
Date:   Wed, 15 Apr 2020 09:07:32 +0400
To:     linux-bluetooth@vger.kernel.org
Sender: linux-bluetooth-owner@vger.kernel.org
Precedence: bulk

I=E2=80=99m working with a QCA9337 SDIO device on an Android (now Linux) =
set-top box with an Amlogic S905D SoC.

SDIO WiFi (ath10k) is working since 5.7-rc1, but the BT side of the =
module is still missing.

Most Amlogic devices (95%+) use Broadcom SDIO modules with the following =
device tree content:

&uart_A {
	bluetooth {
		compatible =3D "brcm,bcm43438-bt";
		shutdown-gpios =3D <&gpio GPIOX_17 GPIO_ACTIVE_HIGH>;
		max-speed =3D <2000000>;
		clocks =3D <&wifi32k>;
		clock-names =3D "lpo";
	};
};

I changed the compatible to "qcom,qca9377-bt=E2=80=9D and applied the =
following patch:

diff --git a/drivers/bluetooth/hci_qca.c b/drivers/bluetooth/hci_qca.c
index 439392b1c043..6f0350fbdcd6 100644
--- a/drivers/bluetooth/hci_qca.c
+++ b/drivers/bluetooth/hci_qca.c
@@ -2046,6 +2046,7 @@ static SIMPLE_DEV_PM_OPS(qca_pm_ops, qca_suspend, =
qca_resume);
=20
 static const struct of_device_id qca_bluetooth_of_match[] =3D {
        { .compatible =3D "qcom,qca6174-bt" },
+       { .compatible =3D "qcom,qca9377-bt" },
        { .compatible =3D "qcom,wcn3990-bt", .data =3D =
&qca_soc_data_wcn3990},
        { .compatible =3D "qcom,wcn3991-bt", .data =3D =
&qca_soc_data_wcn3991},
        { .compatible =3D "qcom,wcn3998-bt", .data =3D =
&qca_soc_data_wcn3998},

This results in probing with errors: http://ix.io/2i6P

I noticed "max-speed =3D <2000000>;=E2=80=9D while hci_qca.c sets =
3000000. I attempted to set "max-speed =3D <3000000>;=E2=80=9D but this =
made no difference, so I patched a lower value in hci_qca:

diff --git a/drivers/bluetooth/hci_qca.c b/drivers/bluetooth/hci_qca.c
index 6f0350fbdcd6..b7ea1e9f4904 100644
--- a/drivers/bluetooth/hci_qca.c
+++ b/drivers/bluetooth/hci_qca.c
@@ -1678,7 +1678,7 @@ static const struct hci_uart_proto qca_proto =3D {
        .name           =3D "QCA",
        .manufacturer   =3D 29,
        .init_speed     =3D 115200,
-       .oper_speed     =3D 3000000,
+       .oper_speed     =3D 2000000,
        .open           =3D qca_open,
        .close          =3D qca_close,
        .flush          =3D qca_flush,

This shows a frame reassembly error, but an attempt to load firmware, =
see: http://ix.io/2i6Q

Using renamed files from =
https://github.com/boundarydevices/qca-firmware/tree/bd-sdmac-ath10k/qca

There is still a "kernel: Bluetooth: hci0: Frame reassembly failed =
(-84)=E2=80=9D error, but the module is now otherwise up/working - I can =
scan/see/pair other BT devices.

see: http://ix.io/2i6S and:

SML5442TW:~ # bluetoothctl show
Controller 91:08:00:00:00:00 (public)
	Name: SML5442TW
	Alias: SML5442TW
	Class: 0x000c0000
	Powered: yes
	Discoverable: no
	DiscoverableTimeout: 0x000000b4
	Pairable: yes
	UUID: Audio Source              =
(0000110a-0000-1000-8000-00805f9b34fb)
	UUID: Generic Attribute Profile =
(00001801-0000-1000-8000-00805f9b34fb)
	UUID: Generic Access Profile    =
(00001800-0000-1000-8000-00805f9b34fb)
	UUID: PnP Information           =
(00001200-0000-1000-8000-00805f9b34fb)
	UUID: A/V Remote Control Target =
(0000110c-0000-1000-8000-00805f9b34fb)
	UUID: A/V Remote Control        =
(0000110e-0000-1000-8000-00805f9b34fb)
	UUID: Audio Sink                =
(0000110b-0000-1000-8000-00805f9b34fb)
	Modalias: usb:v1D6Bp0246d0536
	Discovering: no
Advertising Features:
	ActiveInstances: 0x00
	SupportedInstances: 0x05
	SupportedIncludes: tx-power
	SupportedIncludes: appearance
	SupportedIncludes: local-name

So it looks like hci_qca.c needs modification to handle multiple =
operating speeds, perhaps using the max-speed description from =
device-tree if available, or defaulting to the current 3000000 value if =
not.

I=E2=80=99m not a coding developer so I need to ask for help. If someone =
can suggest a patch - I can test and confirm it works. Or if someone can =
explain how this should be implemented, I can see if I can find someone =
to help with the task.

Christian