linux-kernel - Re: [PATCH v2] serial: qcom_geni: Fix pinctrl deadlock on runtime resume

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Message-ID: <8e2781ae-34d2-4009-bf8c-56aa1bb6fe85@oss.qualcomm.com>
Date: Thu, 18 Sep 2025 09:25:53 +0530
From: Praveen Talari <praveen.talari@....qualcomm.com>
To: Krzysztof Kozlowski <krzk@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jirislaby@...nel.org>,
        Bryan O'Donoghue <bryan.odonoghue@...aro.org>,
        Praveen Talari <quic_ptalari@...cinc.com>,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-serial@...r.kernel.org, alexey.klimov@...aro.org,
        jorge.ramirez@....qualcomm.com, dmitry.baryshkov@....qualcomm.com,
        andersson@...nel.org
Cc: 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 v2] serial: qcom_geni: Fix pinctrl deadlock on runtime
 resume

Hi Krzysztof,

On 9/18/2025 5:28 AM, Krzysztof Kozlowski wrote:
> On 18/09/2025 03:51, Praveen Talari wrote:
>> A stall was observed in disable_irq() during
>> pinctrl_pm_select_default_state(), triggered by wakeup IRQ being active
>> while the UART port was not yet active. This led to a hang in
>> __synchronize_irq(), as shown in the following trace:
>>
>> Call trace:
>>      __switch_to+0xe0/0x120
>>      __schedule+0x39c/0x978
>>      schedule+0x5c/0xf8
>>      __synchronize_irq+0x88/0xb4
>>      disable_irq+0x3c/0x4c
>>      msm_pinmux_set_mux+0x508/0x644
>>      pinmux_enable_setting+0x190/0x2dc
>>      pinctrl_commit_state+0x13c/0x208
>>      pinctrl_pm_select_default_state+0x4c/0xa4
>>      geni_se_resources_on+0xe8/0x154
>>      qcom_geni_serial_runtime_resume+0x4c/0x88
>>      pm_generic_runtime_resume+0x2c/0x44
>>      __genpd_runtime_resume+0x30/0x80
>>      genpd_runtime_resume+0x114/0x29c
>>      __rpm_callback+0x48/0x1d8
>>      rpm_callback+0x6c/0x78
>>      rpm_resume+0x530/0x750
>>      __pm_runtime_resume+0x50/0x94
>>      handle_threaded_wake_irq+0x30/0x94
>>      irq_thread_fn+0x2c/0xa8
>>      irq_thread+0x160/0x248
>>      kthread+0x110/0x114
>>      ret_from_fork+0x10/0x20
>>
>> To fix this, wakeup IRQ setup is moved from probe to UART startup,
>> ensuring it is only configured when the port is active. Correspondingly,
>> the wakeup IRQ is cleared during shutdown. This avoids premature IRQ
>> disable during pinctrl setup and prevents the observed stall. The probe
>> and remove pathsare simplified by removing redundant wakeup IRQ handling.
>>
>> Fixes: 1afa70632c39 ("serial: qcom-geni: Enable PM runtime for serial driver")
>> Reported-by: Alexey Klimov <alexey.klimov@...aro.org>
>> Closes: https://lore.kernel.org/all/DC0D53ZTNOBU.E8LSD5E5Z8TX@linaro.org/
>> Tested-by: Jorge Ramirez <jorge.ramirez@....qualcomm.com>
> 
> Where did you receive this tag for this patch exactly?

Since Jorge was involved in validating the change, I’ve added him under 
the Tested-by tag.

Please correct me if I’m not supposed to add this tag myself.

Thanks,
Praveen Talari

> 
> Best regards,
> Krzysztof