[PATCH v1] arm64: dts: qcom: hamoa-iot-evk: support Bluetooth over both USB and UART

[PATCH v1] arm64: dts: qcom: hamoa-iot-evk: support Bluetooth over both USB and UART

[Shuai Zhang]

When Bluetooth supports both USB and UART, the BT UART driver is
always loaded, while USB is hot-pluggable. As a result, when Bluetooth
is used over USB, the UART driver still be probed and drive BT_EN low,
which causes the Bluetooth device on USB to be disconnected.

Configure BT_EN as a GPIO hog so that it is controlled by the platform
instead of the UART driver, preventing BT over USB from being
unintentionally powered down.

Signed-off-by: Shuai Zhang <shuai.zhang@oss.qualcomm.com>
---
 arch/arm64/boot/dts/qcom/hamoa-iot-evk.dts | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/arch/arm64/boot/dts/qcom/hamoa-iot-evk.dts b/arch/arm64/boot/dts/qcom/hamoa-iot-evk.dts
index 630642baa435..60a0b3ecbc1b 100644
--- a/arch/arm64/boot/dts/qcom/hamoa-iot-evk.dts
+++ b/arch/arm64/boot/dts/qcom/hamoa-iot-evk.dts
@@ -647,10 +647,9 @@ wcn7850-pmu {
 		vddrfa1p2-supply = <&vreg_wcn_1p9>;
 		vddrfa1p8-supply = <&vreg_wcn_1p9>;
 
-		bt-enable-gpios = <&tlmm 116 GPIO_ACTIVE_HIGH>;
 		wlan-enable-gpios = <&tlmm 117 GPIO_ACTIVE_HIGH>;
 
-		pinctrl-0 = <&wcn_bt_en>, <&wcn_wlan_en>;
+		pinctrl-0 = <&wcn_wlan_en>;
 		pinctrl-names = "default";
 
 		regulators {
@@ -1398,11 +1397,12 @@ wcd_default: wcd-reset-n-active-state {
 		output-low;
 	};
 
-	wcn_bt_en: wcn-bt-en-state {
-		pins = "gpio116";
-		function = "gpio";
-		drive-strength = <2>;
-		bias-disable;
+	wcn_bt_en_hog: wcn-bt-en-state-hog {
+		gpio-hog;
+		gpios = <116 GPIO_ACTIVE_HIGH>;
+		output-high;
+		input-disable;
+		link-name = "BT_EN";
 	};
 
 	wcn_wlan_en: wcn-wlan-en-state {
-- 
2.34.1

RE: [v1] arm64: dts: qcom: hamoa-iot-evk: support Bluetooth over both USB and UART

[bluez.test.bot]

[-- Attachment #1: Type: text/plain, Size: 586 bytes --]

This is an automated email and please do not reply to this email.

Dear Submitter,

Thank you for submitting the patches to the linux bluetooth mailing list.
While preparing the CI tests, the patches you submitted couldn't be applied to the current HEAD of the repository.

----- Output -----

error: patch failed: arch/arm64/boot/dts/qcom/hamoa-iot-evk.dts:647
error: arch/arm64/boot/dts/qcom/hamoa-iot-evk.dts: patch does not apply
hint: Use 'git am --show-current-patch' to see the failed patch

Please resolve the issue and submit the patches again.


---
Regards,
Linux Bluetooth

Re: [PATCH v1] arm64: dts: qcom: hamoa-iot-evk: support Bluetooth over both USB and UART

[Konrad Dybcio]

On 3/11/26 10:09 AM, Shuai Zhang wrote:
> When Bluetooth supports both USB and UART, the BT UART driver is
> always loaded, while USB is hot-pluggable. As a result, when Bluetooth
> is used over USB, the UART driver still be probed and drive BT_EN low,
> which causes the Bluetooth device on USB to be disconnected.

Is bluetooth connected over UART *and* USB simultaneously?

> Configure BT_EN as a GPIO hog so that it is controlled by the platform

What's "the platform"?

> instead of the UART driver, preventing BT over USB from being
> unintentionally powered down.
> 
> Signed-off-by: Shuai Zhang <shuai.zhang@oss.qualcomm.com>
> ---
>  arch/arm64/boot/dts/qcom/hamoa-iot-evk.dts | 14 +++++++-------
>  1 file changed, 7 insertions(+), 7 deletions(-)
> 
> diff --git a/arch/arm64/boot/dts/qcom/hamoa-iot-evk.dts b/arch/arm64/boot/dts/qcom/hamoa-iot-evk.dts
> index 630642baa435..60a0b3ecbc1b 100644
> --- a/arch/arm64/boot/dts/qcom/hamoa-iot-evk.dts
> +++ b/arch/arm64/boot/dts/qcom/hamoa-iot-evk.dts
> @@ -647,10 +647,9 @@ wcn7850-pmu {
>  		vddrfa1p2-supply = <&vreg_wcn_1p9>;
>  		vddrfa1p8-supply = <&vreg_wcn_1p9>;
>  
> -		bt-enable-gpios = <&tlmm 116 GPIO_ACTIVE_HIGH>;

What if I want to power down Bluetooth now?

>  		wlan-enable-gpios = <&tlmm 117 GPIO_ACTIVE_HIGH>;
>  
> -		pinctrl-0 = <&wcn_bt_en>, <&wcn_wlan_en>;
> +		pinctrl-0 = <&wcn_wlan_en>;
>  		pinctrl-names = "default";
>  
>  		regulators {
> @@ -1398,11 +1397,12 @@ wcd_default: wcd-reset-n-active-state {
>  		output-low;
>  	};
>  
> -	wcn_bt_en: wcn-bt-en-state {
> -		pins = "gpio116";
> -		function = "gpio";
> -		drive-strength = <2>;
> -		bias-disable;
> +	wcn_bt_en_hog: wcn-bt-en-state-hog {

This name is illegal (make CHECK_DTBS=1 qcom/hamoa-iot-evk.dtb)

> +		gpio-hog;
> +		gpios = <116 GPIO_ACTIVE_HIGH>;
> +		output-high;
> +		input-disable;

This property is not allowed for TLMM pins

> +		link-name = "BT_EN";

This property doesn't exist

Konrad

Re: [PATCH v1] arm64: dts: qcom: hamoa-iot-evk: support Bluetooth over both USB and UART

[Shuai Zhang]

Hi Konrad

On 3/11/2026 9:07 PM, Konrad Dybcio wrote:
> On 3/11/26 10:09 AM, Shuai Zhang wrote:
>> When Bluetooth supports both USB and UART, the BT UART driver is
>> always loaded, while USB is hot-pluggable. As a result, when Bluetooth
>> is used over USB, the UART driver still be probed and drive BT_EN low,
>> which causes the Bluetooth device on USB to be disconnected.
> Is bluetooth connected over UART *and* USB simultaneously?
BT uses either UART or USB, never both at the same time.

On platforms supporting both, the UART driver is always probed, while 
USB is hot‑pluggable.

As a result, when BT runs over USB, the UART driver still probes and 
pulls BT_EN low,

unintentionally powering off the USB BT device.

>
>> Configure BT_EN as a GPIO hog so that it is controlled by the platform
> What's "the platform"?

hamoa-evk


>
>> instead of the UART driver, preventing BT over USB from being
>> unintentionally powered down.
>>
>> Signed-off-by: Shuai Zhang <shuai.zhang@oss.qualcomm.com>
>> ---
>>   arch/arm64/boot/dts/qcom/hamoa-iot-evk.dts | 14 +++++++-------
>>   1 file changed, 7 insertions(+), 7 deletions(-)
>>
>> diff --git a/arch/arm64/boot/dts/qcom/hamoa-iot-evk.dts b/arch/arm64/boot/dts/qcom/hamoa-iot-evk.dts
>> index 630642baa435..60a0b3ecbc1b 100644
>> --- a/arch/arm64/boot/dts/qcom/hamoa-iot-evk.dts
>> +++ b/arch/arm64/boot/dts/qcom/hamoa-iot-evk.dts
>> @@ -647,10 +647,9 @@ wcn7850-pmu {
>>   		vddrfa1p2-supply = <&vreg_wcn_1p9>;
>>   		vddrfa1p8-supply = <&vreg_wcn_1p9>;
>>   
>> -		bt-enable-gpios = <&tlmm 116 GPIO_ACTIVE_HIGH>;
> What if I want to power down Bluetooth now?


It cannot be pulled low because it is not possible to determine whether 
the inserted M.2 card is UART‑based or USB‑based.

Identifying whether the interface is USB or UART would allow control of 
the UART probe accordingly;

however, no reliable solution is available so far. Additional approaches 
are still being explored.


>
>>   		wlan-enable-gpios = <&tlmm 117 GPIO_ACTIVE_HIGH>;
>>   
>> -		pinctrl-0 = <&wcn_bt_en>, <&wcn_wlan_en>;
>> +		pinctrl-0 = <&wcn_wlan_en>;
>>   		pinctrl-names = "default";
>>   
>>   		regulators {
>> @@ -1398,11 +1397,12 @@ wcd_default: wcd-reset-n-active-state {
>>   		output-low;
>>   	};
>>   
>> -	wcn_bt_en: wcn-bt-en-state {
>> -		pins = "gpio116";
>> -		function = "gpio";
>> -		drive-strength = <2>;
>> -		bias-disable;
>> +	wcn_bt_en_hog: wcn-bt-en-state-hog {
> This name is illegal (make CHECK_DTBS=1 qcom/hamoa-iot-evk.dtb)


|I will use tlmm to control|


>
>> +		gpio-hog;
>> +		gpios = <116 GPIO_ACTIVE_HIGH>;
>> +		output-high;
>> +		input-disable;
> This property is not allowed for TLMM pins
>
>> +		link-name = "BT_EN";
> This property doesn't exist


I  will remove it;


>
> Konrad


thanks,
Shuai

Re: [PATCH v1] arm64: dts: qcom: hamoa-iot-evk: support Bluetooth over both USB and UART

[Konrad Dybcio]

On 3/13/26 7:37 AM, Shuai Zhang wrote:
> Hi Konrad
> 
> On 3/11/2026 9:07 PM, Konrad Dybcio wrote:
>> On 3/11/26 10:09 AM, Shuai Zhang wrote:
>>> When Bluetooth supports both USB and UART, the BT UART driver is
>>> always loaded, while USB is hot-pluggable. As a result, when Bluetooth
>>> is used over USB, the UART driver still be probed and drive BT_EN low,
>>> which causes the Bluetooth device on USB to be disconnected.
>> Is bluetooth connected over UART *and* USB simultaneously?
> BT uses either UART or USB, never both at the same time.
> 
> On platforms supporting both, the UART driver is always probed, while USB is hot‑pluggable.
> 
> As a result, when BT runs over USB, the UART driver still probes and pulls BT_EN low,
> 
> unintentionally powering off the USB BT device.

Please describe in more detail how that difference can appear in practice.

Is there an M.2 slot, into which different kinds of cards (i.e. ones with
BT-over-USB vs BT-over-UART) may be plugged in?

Konrad

Re: [PATCH v1] arm64: dts: qcom: hamoa-iot-evk: support Bluetooth over both USB and UART

[Shuai Zhang]

Hi Konrad

Thanks for your review.

On 3/13/2026 8:34 PM, Konrad Dybcio wrote:
> On 3/13/26 7:37 AM, Shuai Zhang wrote:
>> Hi Konrad
>>
>> On 3/11/2026 9:07 PM, Konrad Dybcio wrote:
>>> On 3/11/26 10:09 AM, Shuai Zhang wrote:
>>>> When Bluetooth supports both USB and UART, the BT UART driver is
>>>> always loaded, while USB is hot-pluggable. As a result, when Bluetooth
>>>> is used over USB, the UART driver still be probed and drive BT_EN low,
>>>> which causes the Bluetooth device on USB to be disconnected.
>>> Is bluetooth connected over UART *and* USB simultaneously?
>> BT uses either UART or USB, never both at the same time.
>>
>> On platforms supporting both, the UART driver is always probed, while USB is hot‑pluggable.
>>
>> As a result, when BT runs over USB, the UART driver still probes and pulls BT_EN low,
>>
>> unintentionally powering off the USB BT device.
> Please describe in more detail how that difference can appear in practice.
>
> Is there an M.2 slot, into which different kinds of cards (i.e. ones with
> BT-over-USB vs BT-over-UART) may be plugged in?

Yes, this is an M.2 slot that can accommodate different types of cards.
Additionally, the maintainer proposed option [1], which should be able 
to resolve my issue.

I am currently evaluating it.

[1]https://lore.kernel.org/r/20260224-pci-m2-e-v5-9-dd9b9501d33c@oss.qualcomm.com

>
> Konrad


Thanks,
Shuai

Re: [PATCH v1] arm64: dts: qcom: hamoa-iot-evk: support Bluetooth over both USB and UART

[Konrad Dybcio]

On 3/13/26 7:37 AM, Shuai Zhang wrote:
> Hi Konrad
> 
> On 3/11/2026 9:07 PM, Konrad Dybcio wrote:
>> On 3/11/26 10:09 AM, Shuai Zhang wrote:
>>> When Bluetooth supports both USB and UART, the BT UART driver is
>>> always loaded, while USB is hot-pluggable. As a result, when Bluetooth
>>> is used over USB, the UART driver still be probed and drive BT_EN low,
>>> which causes the Bluetooth device on USB to be disconnected.
>> Is bluetooth connected over UART *and* USB simultaneously?
> BT uses either UART or USB, never both at the same time.

[...]

>>>   -    wcn_bt_en: wcn-bt-en-state {
>>> -        pins = "gpio116";
>>> -        function = "gpio";
>>> -        drive-strength = <2>;
>>> -        bias-disable;
>>> +    wcn_bt_en_hog: wcn-bt-en-state-hog {
>> This name is illegal (make CHECK_DTBS=1 qcom/hamoa-iot-evk.dtb)
> 
> 
> |I will use tlmm to control|
> 
> 
>>
>>> +        gpio-hog;
>>> +        gpios = <116 GPIO_ACTIVE_HIGH>;
>>> +        output-high;
>>> +        input-disable;
>> This property is not allowed for TLMM pins
>>
>>> +        link-name = "BT_EN";
>> This property doesn't exist
> 
> 
> I  will remove it;

Please run

make [...] CHECK_DTBS=1 qcom/hamoa-iot-evk.dtb

for your next submission to ensure the schema checks succeed

Konrad

Re: [PATCH v1] arm64: dts: qcom: hamoa-iot-evk: support Bluetooth over both USB and UART

[Dmitry Baryshkov]

On Fri, Mar 13, 2026 at 02:37:39PM +0800, Shuai Zhang wrote:
> Hi Konrad
> 
> On 3/11/2026 9:07 PM, Konrad Dybcio wrote:
> > On 3/11/26 10:09 AM, Shuai Zhang wrote:
> > > When Bluetooth supports both USB and UART, the BT UART driver is
> > > always loaded, while USB is hot-pluggable. As a result, when Bluetooth
> > > is used over USB, the UART driver still be probed and drive BT_EN low,
> > > which causes the Bluetooth device on USB to be disconnected.
> > Is bluetooth connected over UART *and* USB simultaneously?
> BT uses either UART or USB, never both at the same time.
> 
> On platforms supporting both, the UART driver is always probed, while USB is
> hot‑pluggable.
> 
> As a result, when BT runs over USB, the UART driver still probes and pulls
> BT_EN low,
> 
> unintentionally powering off the USB BT device.

Could you please confirm if [1] would solve the problem?


[1] https://lore.kernel.org/r/20260224-pci-m2-e-v5-9-dd9b9501d33c@oss.qualcomm.com

> 
> > 
> > > Configure BT_EN as a GPIO hog so that it is controlled by the platform
> > What's "the platform"?
> 
> hamoa-evk
> 
> 

-- 
With best wishes
Dmitry

RE: [v1] arm64: dts: qcom: hamoa-iot-evk: support Bluetooth over both USB and UART

[bluez.test.bot]

[-- Attachment #1: Type: text/plain, Size: 3000 bytes --]

This is automated email and please do not reply to this email!

Dear submitter,

Thank you for submitting the patches to the linux bluetooth mailing list.
This is a CI test results with your patch series:
PW Link:https://patchwork.kernel.org/project/bluetooth/list/?series=1064914

---Test result---

Test Summary:
CheckPatch                    PENDING   0.36 seconds
GitLint                       PENDING   0.25 seconds
SubjectPrefix                 FAIL      0.41 seconds
BuildKernel                   PASS      26.51 seconds
CheckAllWarning               PASS      29.59 seconds
CheckSparse                   PASS      27.97 seconds
BuildKernel32                 PASS      25.97 seconds
TestRunnerSetup               PASS      578.09 seconds
TestRunner_l2cap-tester       PASS      28.13 seconds
TestRunner_iso-tester         FAIL      35.02 seconds
TestRunner_bnep-tester        PASS      6.46 seconds
TestRunner_mgmt-tester        FAIL      115.32 seconds
TestRunner_rfcomm-tester      PASS      9.76 seconds
TestRunner_sco-tester         FAIL      14.43 seconds
TestRunner_ioctl-tester       PASS      10.54 seconds
TestRunner_mesh-tester        FAIL      12.58 seconds
TestRunner_smp-tester         PASS      8.80 seconds
TestRunner_userchan-tester    PASS      6.74 seconds
IncrementalBuild              PENDING   0.51 seconds

Details
##############################
Test: CheckPatch - PENDING
Desc: Run checkpatch.pl script
Output:

##############################
Test: GitLint - PENDING
Desc: Run gitlint
Output:

##############################
Test: SubjectPrefix - FAIL
Desc: Check subject contains "Bluetooth" prefix
Output:
"Bluetooth: " prefix is not specified in the subject
##############################
Test: TestRunner_iso-tester - FAIL
Desc: Run iso-tester with test-runner
Output:
BUG: KASAN: slab-use-after-free in le_read_features_complete+0x7e/0x2b0
Total: 141, Passed: 141 (100.0%), Failed: 0, Not Run: 0
##############################
Test: TestRunner_mgmt-tester - FAIL
Desc: Run mgmt-tester with test-runner
Output:
Total: 494, Passed: 489 (99.0%), Failed: 1, Not Run: 4

Failed Test Cases
Read Exp Feature - Success                           Failed       0.102 seconds
##############################
Test: TestRunner_sco-tester - FAIL
Desc: Run sco-tester with test-runner
Output:
WARNING: possible circular locking dependency detected
BUG: sleeping function called from invalid context at net/core/sock.c:3782
Total: 30, Passed: 30 (100.0%), Failed: 0, Not Run: 0
##############################
Test: TestRunner_mesh-tester - FAIL
Desc: Run mesh-tester with test-runner
Output:
Total: 10, Passed: 8 (80.0%), Failed: 2, Not Run: 0

Failed Test Cases
Mesh - Send cancel - 1                               Timed out    2.769 seconds
Mesh - Send cancel - 2                               Timed out    1.994 seconds
##############################
Test: IncrementalBuild - PENDING
Desc: Incremental build with the patches in the series
Output:



---
Regards,
Linux Bluetooth