linux-kernel - Re: [PATCH v1] serial: qcom-geni: Fix pinctrl deadlock on runtime resume

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Message-ID: <aMl2hOYTjBuCo4AM@trex>
Date: Tue, 16 Sep 2025 16:39:00 +0200
From: Jorge Ramirez <jorge.ramirez@....qualcomm.com>
To: Praveen Talari <praveen.talari@....qualcomm.com>
Cc: Alexey Klimov <alexey.klimov@...aro.org>,
        Praveen Talari <quic_ptalari@...cinc.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jirislaby@...nel.org>,
        Bryan O'Donoghue <bryan.odonoghue@...aro.org>,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-serial@...r.kernel.org, psodagud@...cinc.com, djaggi@...cinc.com,
        quic_msavaliy@...cinc.com, quic_vtanuku@...cinc.com,
        quic_arandive@...cinc.com, quic_shazhuss@...cinc.com, krzk@...nel.org
Subject: Re: [PATCH v1] serial: qcom-geni: Fix pinctrl deadlock on runtime
 resume

On 16/09/25 12:20:25, Praveen Talari wrote:
> Hi Alexey
> 
> Thank you for your support.
> 
> On 9/15/2025 7:55 PM, Praveen Talari wrote:
> > Hi Alexey,
> > 
> > On 9/15/2025 3:09 PM, Alexey Klimov wrote:
> > > (removing <quic_mnaresh@...cinc.com> from c/c -- too many mail not
> > > delivered)
> > > 
> > > Hi Praveen,
> > > 
> > > On Mon Sep 15, 2025 at 7:58 AM BST, Praveen Talari wrote:
> > > > Hi Alexey,
> > > > 
> > > > Really appreciate you waiting!
> > > > 
> > > > On 9/11/2025 2:30 PM, Alexey Klimov wrote:
> > > > > Hi Praveen,
> > > > > 
> > > > > On Thu Sep 11, 2025 at 9:34 AM BST, Praveen Talari wrote:
> > > > > > Hi Alexy,
> > > > > > 
> > > > > > Thank you for update.
> > > > > > 
> > > > > > On 9/10/2025 1:35 AM, Alexey Klimov wrote:
> > > > > > > 
> > > > > > > (adding Krzysztof to c/c)
> > > > > > > 
> > > > > > > On Mon Sep 8, 2025 at 6:43 PM BST, Alexey Klimov wrote:
> > > > > > > > On Mon Sep 8, 2025 at 5:45 PM BST, Praveen Talari wrote:
> > > > > > > > > A deadlock is observed in the
> > > > > > > > > qcom_geni_serial driver during runtime
> > > > > > > > > resume. This occurs when the pinctrl
> > > > > > > > > subsystem reconfigures device pins
> > > > > > > > > via msm_pinmux_set_mux() while the serial device's interrupt is an
> > > > > > > > > active wakeup source. msm_pinmux_set_mux() calls disable_irq() or
> > > > > > > > > __synchronize_irq(), conflicting with the active wakeup state and
> > > > > > > > > causing the IRQ thread to enter an uninterruptible (D-state) sleep,
> > > > > > > > > leading to system instability.
> > > > > > > > > 
> > > > > > > > > The critical call trace leading to the deadlock is:
> > > > > > > > > 
> > > > > > > > >        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/xa8
> > > > > > > > >        irq_thread+0x160/x248
> > > > > > > > >        kthread+0x110/x114
> > > > > > > > >        ret_from_fork+0x10/x20
> > > > > > > > > 
> > > > > > > > > To resolve this, explicitly manage the wakeup IRQ state within the
> > > > > > > > > runtime suspend/resume callbacks. In the
> > > > > > > > > runtime resume callback, call
> > > > > > > > > disable_irq_wake() before enabling resources. This preemptively
> > > > > > > > > removes the "wakeup" capability from the IRQ, allowing subsequent
> > > > > > > > > interrupt management calls to proceed
> > > > > > > > > without conflict. An error path
> > > > > > > > > re-enables the wakeup IRQ if resource enablement fails.
> > > > > > > > > 
> > > > > > > > > Conversely, in runtime suspend, call
> > > > > > > > > enable_irq_wake() after resources
> > > > > > > > > are disabled. This ensures the interrupt is configured as a wakeup
> > > > > > > > > source only once the device has fully
> > > > > > > > > entered its low-power state. An
> > > > > > > > > error path handles disabling the wakeup IRQ
> > > > > > > > > if the suspend operation
> > > > > > > > > fails.
> > > > > > > > > 
> > > > > > > > > Fixes: 1afa70632c39 ("serial: qcom-geni:
> > > > > > > > > Enable PM runtime for serial driver")
> > > > > > > > > Signed-off-by: Praveen Talari <praveen.talari@....qualcomm.com>
> > > > > > > > 
> > > > > > > > You forgot:
> > > > > > > > 
> > > > > > > > Reported-by: Alexey Klimov <alexey.klimov@...aro.org>
> > > > > > > > 
> > > > > > > > Also, not sure where this change will go, via
> > > > > > > > Greg or Jiri, but ideally
> > > > > > > > this should be picked for current -rc cycle since regression is
> > > > > > > > introduced during latest merge window.
> > > > > > > > 
> > > > > > > > I also would like to test it on qrb2210 rb1 where this regression is
> > > > > > > > reproduciable.
> 
> Since I don't have this board, could you kindly validate the new change and
> run a quick test on your end?
> 
> diff --git a/drivers/pinctrl/qcom/pinctrl-msm.c
> b/drivers/pinctrl/qcom/pinctrl-msm.c
> index 83eb075b6bfa..3d6601dc6fcc 100644
> --- a/drivers/pinctrl/qcom/pinctrl-msm.c
> +++ b/drivers/pinctrl/qcom/pinctrl-msm.c
> @@ -215,7 +215,7 @@ static int msm_pinmux_set_mux(struct pinctrl_dev
> *pctldev,
>          */
>         if (d && i != gpio_func &&
>             !test_and_set_bit(d->hwirq, pctrl->disabled_for_mux))
> -               disable_irq(irq);
> +               disable_irq_nosync(irq);
> 
>         raw_spin_lock_irqsave(&pctrl->lock, flags);


sorry Praveen, didnt see this proposal. testing on my end as well.