linux-kernel - Re: [PATCH] usb: dwc3: Clear DWC3_EVENT

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Message-ID: <20230109183545.kqej7vmtf5o6ihq4@synopsys.com>
Date:   Mon, 9 Jan 2023 18:35:48 +0000
From:   Thinh Nguyen <Thinh.Nguyen@...opsys.com>
To:     JaeHun Jung <jh0801.jung@...sung.com>
CC:     Felipe Balbi <balbi@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "open list:USB XHCI DRIVER" <linux-usb@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>,
        Seungchull Suh <sc.suh@...sung.com>,
        Daehwan Jung <dh10.jung@...sung.com>
Subject: Re: [PATCH] usb: dwc3: Clear DWC3_EVENT_PENDING when count is 0

Hi,

On Mon, Jan 02, 2023, 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.
> So, It have to clean up DWC3_EVENT_PENDING flags set when count is 0.
> It means "There are no interrupts to handle.".

Can you reword to include the explanation from my response [*] and add a
fixes tag to 7441b273388b ("usb: dwc3: gadget: Fix event pending check")

Thanks,
Thinh

[*] https://lore.kernel.org/linux-usb/20230109182813.sle5h34wdgglnlph@synopsys.com/T/#md32deea7e6b3c6d309aadba3d1cd2800d173685e


> 
> (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@...sung.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;
> -- 
> 2.31.1
>