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From: Peter Chen <>
To: Jeaho Hwang <>
	"변무광(Byeon Moo Kwang)/자동화연)Automation Platform연구팀"
	<>, "Linux team" <>
Subject: Re: Chipidea USB device goes infinite loop due to interrupt while hw_ep_prime
Date: Wed, 4 Aug 2021 09:32:52 +0800	[thread overview]
Message-ID: <20210804013252.GA16420@nchen> (raw)
In-Reply-To: <>

On 21-08-02 17:35:01, Jeaho Hwang wrote:
> Hi.
> We found an infinite loop inside the function hw_ep_set_halt
> (drivers/usb/chipidea/udc.c) if a cablle is repeatedly
> connnected/disconnected while ping through RNDIS with chipidea USB device.
> Using ftrace tracing, we found that hw_ep_set_halt is called due to error
> return of hw_ep_prime(drivers/usb/chipidea/udc.c:202) which is called from
> isr_tr_complete_handler -> isr_setup_status_phase -> _ep_queue.
> The comment of function hw_ep_prime says (execute without interruption) but
> timer interrupt is occurred while hw_ep_prime is executing. We believe that
> the interrupt causes an error return of hw_ep_prime. We tried to protect
> hw_ep_prime from irqs and then no case of the infinite loop is occurred.
> I want ask if it is appropriate way that turning off irq inside (threaded)
> irq handlers. And should we explicitly turn off irqs before calling
> hw_ep_prime?

Jeaho, do you use RT-Linux or standard Linux? The function hw_ep_prime is
only called at udc_irq which is registered as top-half irq handlers.
Why the timer interrupt is occurred when hw_ep_prime is executing?


Peter Chen

       reply	other threads:[~2021-08-04  1:32 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <>
2021-08-04  1:32 ` Peter Chen [this message]
2021-08-04  2:03   ` Chipidea USB device goes infinite loop due to interrupt while hw_ep_prime Jeaho Hwang
2021-08-09  1:27     ` Peter Chen
2021-08-09  1:45       ` Jeaho Hwang
2021-08-09  6:31         ` Peter Chen
2021-08-04  3:11   ` Jeaho Hwang
2021-08-09  1:40     ` Peter Chen
2021-08-02  8:38 Jeaho Hwang

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