linux-kernel - Re: [PATCH 4/5] usb: dwc3: qcom: Clear pending interrupt before enabling wake interrupt

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Message-ID: <ZCKzQA1YhXQ/6n3L@hovoldconsulting.com>
Date:   Tue, 28 Mar 2023 11:28:32 +0200
From:   Johan Hovold <johan@...nel.org>
To:     Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
Cc:     andersson@...nel.org, Thinh.Nguyen@...opsys.com,
        gregkh@...uxfoundation.org, mathias.nyman@...el.com,
        konrad.dybcio@...aro.org, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, linux-arm-msm@...r.kernel.org,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH 4/5] usb: dwc3: qcom: Clear pending interrupt before
 enabling wake interrupt

On Sat, Mar 25, 2023 at 10:22:16PM +0530, Manivannan Sadhasivam wrote:
> It is possible that there may be a pending interrupt logged into the dwc IP
> while the interrupts were disabled in the driver. And when the wakeup
> interrupt is enabled, the pending interrupt might fire which is not
> required to be serviced by the driver.
> 
> So always clear the pending interrupt before enabling wake interrupt.
> 
> Cc: stable@...r.kernel.org # 5.20
> Fixes: 360e8230516d ("usb: dwc3: qcom: Add helper functions to enable,disable wake irqs")
> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
> ---
>  drivers/usb/dwc3/dwc3-qcom.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/usb/dwc3/dwc3-qcom.c b/drivers/usb/dwc3/dwc3-qcom.c
> index bbf67f705d0d..f1059dfcb0e8 100644
> --- a/drivers/usb/dwc3/dwc3-qcom.c
> +++ b/drivers/usb/dwc3/dwc3-qcom.c
> @@ -346,6 +346,8 @@ static void dwc3_qcom_enable_wakeup_irq(int irq, unsigned int polarity)
>  	if (!irq)
>  		return;
>  
> +	irq_set_irqchip_state(irq, IRQCHIP_STATE_PENDING, 0);
> +

This looks like a hack (and a layering violation). Note that there are
no other non-irqchip drivers calling this function.

>  	if (polarity)
>  		irq_set_irq_type(irq, polarity);

Johan