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

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Message-Id: <DCUE5AXJ99BG.150SRQMY7EJG6@linaro.org>
Date: Tue, 16 Sep 2025 18:12:41 +0100
From: "Alexey Klimov" <alexey.klimov@...aro.org>
To: "Praveen Talari" <praveen.talari@....qualcomm.com>, "Praveen Talari"
 <quic_ptalari@...cinc.com>
Cc: "Jorge Ramirez" <jorge.ramirez@....qualcomm.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

Hi Praveen,

On Tue Sep 16, 2025 at 4:07 PM BST, Jorge Ramirez wrote:
> On 16/09/25 16:39:00, Jorge Ramirez wrote:
>> 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.
>> 
>
> just tested on my end and all modules load - deadlocked before this
> update so there is progress (now we can load the network driver)

Is it supposed to be orginal patch here plus disable_irq_nosync()?
Meaning changes for qcom_geni_serial_runtime_{suspend,resume}
+ disable_irq_nosync() in msm_pinmux_set_mux()?

It seems to work here but let me know few more runs.

Best regards,
Alexey