Messages in this thread | | | Date | Tue, 10 Jan 2023 09:56:14 +0800 | Subject | Re: [PATCH] usb: dwc3: Clear DWC3_EVENT_PENDING when count is 0 | From | Linyu Yuan <> |
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On 1/10/2023 2:28 AM, Thinh Nguyen wrote: > On Fri, Jan 06, 2023, Linyu Yuan wrote: >> On 1/5/2023 5:54 PM, 정재훈 wrote: >>>> -----Original Message----- >>>> From: Linyu Yuan [mailto:quic_linyyuan@quicinc.com] >>>> Sent: Thursday, January 5, 2023 12:35 PM >>>> To: JaeHun Jung; Felipe Balbi; Greg Kroah-Hartman; Thinh Nguyen >>>> Cc: open list:USB XHCI DRIVER; open list; Seungchull Suh; Daehwan Jung >>>> Subject: Re: [PATCH] usb: dwc3: Clear DWC3_EVENT_PENDING when count is 0 >>>> >>>> >>>> On 1/5/2023 11:29 AM, Linyu Yuan wrote: >>>>> On 1/2/2023 1:08 PM, JaeHun Jung wrote: >>>>>> Sometimes very rarely, The count is 0 and the DWC3 flag is set has >>>>>> status. >>>>>> It must not have these status. Because, It can make happen interrupt >>>>>> storming status. >>>>> could you help explain without clear the flag, how interrupt storming >>>>> happen ? >>>>> >>>>> as your change didn't touch any hardware register, i don't know how it >>>>> fix storming. >>>>> >>> H/W interrupts are still occur on IP. >> I guess we should fix it from IP layer. >> > How are you certain the problem is from IP layer?
I think all IRQ is from DWC3 controller IP. if it is not IP layer, could you share how to prevent from SW layer ?
seem IRQ can happen when event count is zero , why this can happen ? does it mean event count register is not trust ?
> >> but when checking DWC3_EVENT_PENDING flag, it will auto clear in dwc3 thread >> irq handler. >> >> there is one possible root cause is it cleared only after irq enabled in >> dwc3_process_event_buf(), >> >> we should move unmask irq operation at end of this function. >> > This interrupt storm can happen because we clear the evt->flags _after_ > we unmask the interrupt. This was done to prevent false interrupt from > delay interrupt deassertion, which can be a problem for legacy pci > interrupt. thanks for explain, i didn't know that. > > see 7441b273388b ("usb: dwc3: gadget: Fix event pending check") > > The change JaeHun Jung did should be fine. agree. > BR, > Thinh
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