linux-kernel - Re: [PATCH v1] serial: qcom_geni: Fix BT failure regression on RB2 platform

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Message-ID: <be79091d-3b2d-41bd-9303-2c8a64dde9c4@oss.qualcomm.com>
Date: Wed, 7 Jan 2026 12:36:03 +0530
From: Praveen Talari <praveen.talari@....qualcomm.com>
To: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jirislaby@...nel.org>, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-serial@...r.kernel.org,
        bryan.odonoghue@...aro.org, andersson@...nel.org, psodagud@...cinc.com,
        djaggi@...cinc.com, quic_msavaliy@...cinc.com,
        quic_vtanuku@...cinc.com, quic_arandive@...cinc.com,
        quic_shazhuss@...cinc.com, quic_cchiluve@...cinc.com
Subject: Re: [PATCH v1] serial: qcom_geni: Fix BT failure regression on RB2
 platform

Hi Dmistry,

On 1/7/2026 12:24 PM, Dmitry Baryshkov wrote:
> On Wed, 7 Jan 2026 at 08:48, Praveen Talari
> <praveen.talari@....qualcomm.com> wrote:
>>
>> A regression in linux-next causes Bluetooth functionality to fail during
> 
> linux-next is an ephemeral thing. Please reference the exact commit.
> 
>> bootup on the RB2 platform, preventing proper BT initialization. However,
>> BT works correctly after bootup completes.
>>
>> The issue occurs when runtime PM is enabled and uart_add_one_port() is
>> called before wakeup IRQ setup. The uart_add_one_port() call activates the
>> device through runtime PM, which configures GPIOs to their default state.
>> When wakeup IRQ registration happens afterward, it conflicts with these
>> GPIO settings, causing state corruption that breaks Bluetooth
>> functionality.
> 
> How does it "conflict with GPIO settings", what is "state corruption"?

I mean the issue occurs because the GPIO state is being altered during 
the wakeup source registration process..

Thanks,
Praveen Talari
> 
> 
>>
>> Fix this by moving runtime PM enablement and uart_add_one_port() after
>> wakeup IRQ registration, ensuring proper initialization order.
>>
>> Reported-by: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
>> Closes:
>> https://lore.kernel.org/all/20251110101043.2108414-4-praveen.talari@oss.qualcomm.com/
>> Fixes: 10904d725f6e ("serial: qcom-geni: Enable PM runtime for serial driver")
>> Signed-off-by: Praveen Talari <praveen.talari@....qualcomm.com>
>> ---
>>   drivers/tty/serial/qcom_geni_serial.c | 12 ++++++------
>>   1 file changed, 6 insertions(+), 6 deletions(-)
>>
> 
> Tested-by: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
> 
>