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    SubjectRe: [PATCH] usb: dwc3: Clear DWC3_EVENT_PENDING when count is 0
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    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.


    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.


    > But. ISR doesn't handle it. Because of this
    > "if (evt->flags & DWC3_EVENT_PENDING)"
    >
    > This is event values.
    > (struct dwc3_event_buffer *) ev_buf = 0xFFFFFF883DBF1180 = kernel_size_le_lo32+0xFFFFFF883B391180 -> (
    > (void *) buf = 0xFFFFFFC00DBDD000 = end+0x337D000 -> ,
    > (void *) cache = 0xFFFFFF8839F54080 = kernel_size_le_lo32+0xFFFFFF88376F4080 -> ,
    > (unsigned int) length = 0x1000,
    > (unsigned int) lpos = 0x0,
    > (unsigned int) count = 0x0,
    > (unsigned int) flags = 0x00100001,
    > (dma_addr_t) dma = 0x00000008BD7D7000,
    >
    > *((struct dwc3_event_type *) 0xFFFFFF8839F54080) = (
    > is_devspec = 1,
    > type = 0,
    > reserved8_31 = 774)
    >
    > *((struct dwc3_event_devt *) 0xFFFFFF8839F54080) = (
    > one_bit = 1,
    > device_event = 0,
    > type = 6, << DWC3_DEVICE_EVENT_SUSPEND
    > reserved15_12 = 0,
    > event_info = 3,
    > reserved31_25 = 0)
    >
    > Occurred interrupts are "DWC3_DEVICE_EVENT_SUSPEND".
    > If when "count has 0" and DWC3_EVENT_PENDING are set at the same time than
    > ISR and bottom thread couldn't handle next interrupt.
    > We guessing connected with "dwc3_gadget_process_pending_events()" function.
    > But, We could not find reproduce way.
    >
    >
    >>> storming from software layer ?
    >>>
    >>>> So, It have to clean up DWC3_EVENT_PENDING flags set when count is 0.
    >>>> It means "There are no interrupts to handle.".
    >>>>
    >>>> (struct dwc3_event_buffer *) ev_buf = 0xFFFFFF883DBF1180 (
    >>>> (void *) buf = 0xFFFFFFC00DBDD000 = end+0x337D000,
    >>>> (void *) cache = 0xFFFFFF8839F54080,
    >>>> (unsigned int) length = 0x1000,
    >>>> (unsigned int) lpos = 0x0,
    >>>> (unsigned int) count = 0x0,
    >>>> (unsigned int) flags = 0x00000001,
    >>>> (dma_addr_t) dma = 0x00000008BD7D7000,
    >>>> (struct dwc3 *) dwc = 0xFFFFFF8839CBC880,
    >>>> (u64) android_kabi_reserved1 = 0x0),
    >>>>
    >>>> (time = 47557628930999, irq = 165, fn = dwc3_interrupt, latency = 0,
    >>>> en = 1), (time = 47557628931268, irq = 165, fn = dwc3_interrupt,
    >>>> latency = 0, en = 3), (time = 47557628932383, irq = 165, fn =
    >>>> dwc3_interrupt, latency = 0, en = 1), (time = 47557628932652, irq =
    >>>> 165, fn = dwc3_interrupt, latency = 0, en = 3), (time =
    >>>> 47557628933768, irq = 165, fn = dwc3_interrupt, latency = 0, en = 1),
    >>>> (time = 47557628934037, irq = 165, fn = dwc3_interrupt, latency = 0,
    >>>> en = 3), (time = 47557628935152, irq = 165, fn = dwc3_interrupt,
    >>>> latency = 0, en = 1), (time = 47557628935460, irq = 165, fn =
    >>>> dwc3_interrupt, latency = 0, en = 3), (time = 47557628936575, irq =
    >>>> 165, fn = dwc3_interrupt, latency = 0, en = 1), (time =
    >>>> 47557628936845, irq = 165, fn = dwc3_interrupt, latency = 0, en = 3),
    >>>> (time = 47557628937960, irq = 165, fn = dwc3_interrupt, latency = 0,
    >>>> en = 1), (time = 47557628938229, irq = 165, fn = dwc3_interrupt,
    >>>> latency = 0, en = 3), (time = 47557628939345, irq = 165, fn =
    >>>> dwc3_interrupt, latency = 0, en = 1), (time = 47557628939652, irq =
    >>>> 165, fn = dwc3_interrupt, latency = 0, en = 3), (time =
    >>>> 47557628940768, irq = 165, fn = dwc3_interrupt, latency = 0, en = 1),
    >>>> (time = 47557628941037, irq = 165, fn = dwc3_interrupt, latency = 0,
    >>>> en = 3), (time = 47557628942152, irq = 165, fn = dwc3_interrupt,
    >>>> latency = 0, en = 1), (time = 47557628942422, irq = 165, fn =
    >>>> dwc3_interrupt, latency = 0, en = 3), (time = 47557628943537, irq =
    >>>> 165, fn = dwc3_interrupt, latency = 0, en = 1), (time =
    >>>> 47557628943806, irq = 165, fn = dwc3_interrupt, latency = 0, en = 3),
    >>>> (time = 47557628944922, irq = 165, fn = dwc3_interrupt, latency = 0,
    >>>> en = 1), (time = 47557628945229, irq = 165, fn = dwc3_interrupt,
    >>>> latency = 0, en = 3), (time = 47557628946345, irq = 165, fn =
    >>>> dwc3_interrupt, latency = 0, en = 1), (time = 47557628946614, irq =
    >>>> 165, fn = dwc3_interrupt, latency = 0, en = 3), (time =
    >>>> 47557628947729, irq = 165, fn = dwc3_interrupt, latency = 0, en = 1),
    >>>> (time = 47557628947999, irq = 165, fn = dwc3_interrupt, latency = 0,
    >>>> en = 3),
    >>>>
    >>>> Signed-off-by: JaeHun Jung <jh0801.jung@samsung.com>
    >>>> ---
    >>>> drivers/usb/dwc3/gadget.c | 5 ++++-
    >>>> 1 file changed, 4 insertions(+), 1 deletion(-) diff --git
    >>>> a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c index
    >>>> 789976567f9f..5d2d5a9b9915 100644
    >>>> --- a/drivers/usb/dwc3/gadget.c
    >>>> +++ b/drivers/usb/dwc3/gadget.c
    >>>> @@ -4355,8 +4355,11 @@ static irqreturn_t dwc3_check_event_buf(struct
    >>>> dwc3_event_buffer *evt)
    >>>> * irq event handler completes before caching new event to
    >>>> prevent
    >>>> * losing events.
    >>>> */
    >>>> - if (evt->flags & DWC3_EVENT_PENDING)
    >>>> + if (evt->flags & DWC3_EVENT_PENDING) {
    >>>> + if (!evt->count)
    >>>> + evt->flags &= ~DWC3_EVENT_PENDING;
    >>>> return IRQ_HANDLED;
    >>>> + }
    >>>> count = dwc3_readl(dwc->regs, DWC3_GEVNTCOUNT(0));
    >>>> count &= DWC3_GEVNTCOUNT_MASK;
    >>> how about below change ?
    >>>
    >>> count = dwc3_readl(dwc->regs, DWC3_GEVNTCOUNT(0));
    >>> count &= DWC3_GEVNTCOUNT_MASK;
    >>> - if (!count)
    >>> + if (!count) {
    >>> + evt->flags &= ~DWC3_EVENT_PENDING;
    >>> return IRQ_NONE;
    >>> + }
    >> ignore my suggestion, add Thinh to comment.
    >>> evt->count = count;
    >>> evt->flags |= DWC3_EVENT_PENDING;
    >>>

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