From: Linyu Yuan <quic_linyyuan@quicinc.com>
To: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
Cc: 정재훈 <jh0801.jung@samsung.com>,
"'Felipe Balbi'" <balbi@kernel.org>,
"'Greg Kroah-Hartman'" <gregkh@linuxfoundation.org>,
"'open list:USB XHCI DRIVER'" <linux-usb@vger.kernel.org>,
"'open list'" <linux-kernel@vger.kernel.org>,
"'Seungchull Suh'" <sc.suh@samsung.com>,
"'Daehwan Jung'" <dh10.jung@samsung.com>
Subject: Re: [PATCH] usb: dwc3: Clear DWC3_EVENT_PENDING when count is 0
Date: Thu, 2 Feb 2023 13:00:26 +0800 [thread overview]
Message-ID: <4723be6d-a9c5-17f4-f8d4-6ab0e81d866e@quicinc.com> (raw)
In-Reply-To: <20230201185742.lc26zheeuhvfuxet@synopsys.com>
On 2/2/2023 2:57 AM, Thinh Nguyen wrote:
> On Tue, Jan 31, 2023, Linyu Yuan wrote:
>> hi Thinh,
>>
>>
>> regarding your suggestion, assume it is not PCIe type, still have one
>> question,
>>
>>
>> - if (evt->flags & DWC3_EVENT_PENDING)
>> + if (evt->flags & DWC3_EVENT_PENDING) {
>> + if (!evt->count) {
>> + u32 reg = dwc3_readl(dwc->regs, DWC3_GEVNTSIZ(0));
>> +
>> + if (!(reg & DWC3_GEVNTSIZ_INTMASK))
>> + evt->flags &= ~DWC3_EVENT_PENDING;
>>
>> do we need to return IRQ_WAKE_THREAD ?
> No, if evt->count is 0, but GEVNTCOUNT is > 0, the controller will
> generate interrupt. The evt->count will be updated and the events will
> be handled on the next interrupt.
when will next interrupt happen ?
as when enter here, i guess GEVENTCOUNT is already > 0, but we didn't
read it.
>
>> + }
>> return IRQ_HANDLED;
>>
>> as here return IRQ HANDLED, how can we make sure a new IRQ will be handled
>> after previous IRQ thread clean PENDING flag ?
> If evt->count > 0, that means the bottom half is still running. So,
> leave it be. If evt->count == 0, then the cached events are processed,
> we're safe to clear the PENDING flag. New interrupt will be generated if
> GEVNTCOUNT is > 0.
>
>> + }
>>
>>
>> also for non-PCIe controller, consider IRQ mask register working correctly,
>>
>> consider a case IRQ happen before IRQ thread exit, here just return
>> IRQ_HANDLED.
>>
>> once IRQ thread exit, it will clean PENDING flag, so next IRQ event will run
>> normally.
>>
>> if 정재훈 saw PENDING flag is not cleared, does it mean IRQ thread have no
>> chance to exit ?
> The PENDING flag should be cleared eventually when the bottom half
> completes. I don't expect the interrupt storm to block the IRQ thread
> forever, but I can't guarantee the device behavor. 정재훈 can confirm.
> This change should resolve the interrupt storm.
>
> BR,
> Thinh
next prev parent reply other threads:[~2023-02-02 5:00 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CGME20230102050839epcas2p4b9d09d926f9a14c3b8e8df2574d334c3@epcas2p4.samsung.com>
2023-01-02 5:08 ` [PATCH] usb: dwc3: Clear DWC3_EVENT_PENDING when count is 0 JaeHun Jung
2023-01-03 15:48 ` Felipe Balbi
2023-01-05 3:29 ` Linyu Yuan
2023-01-05 3:35 ` Linyu Yuan
2023-01-05 9:54 ` 정재훈
2023-01-06 3:13 ` Linyu Yuan
2023-01-09 18:28 ` Thinh Nguyen
2023-01-10 1:56 ` Linyu Yuan
2023-01-10 2:53 ` Thinh Nguyen
2023-01-10 3:05 ` Linyu Yuan
2023-01-10 3:13 ` Linyu Yuan
2023-01-10 7:38 ` Linyu Yuan
2023-01-11 0:00 ` Thinh Nguyen
2023-01-11 1:45 ` Linyu Yuan
2023-01-11 2:27 ` Thinh Nguyen
2023-01-31 6:38 ` Linyu Yuan
2023-02-01 18:57 ` Thinh Nguyen
2023-02-02 5:00 ` Linyu Yuan [this message]
2023-02-02 20:06 ` Thinh Nguyen
2023-02-03 2:18 ` Linyu Yuan
2023-01-09 18:35 ` Thinh Nguyen
2023-01-09 19:09 ` Thinh Nguyen
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