linux-kernel - Re: [PATCH] usb: dwc3: qcom: Add shutdown handler

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Message-ID: <20250729221913.33qgxhb77f5hl5df@synopsys.com>
Date: Tue, 29 Jul 2025 22:19:14 +0000
From: Thinh Nguyen <Thinh.Nguyen@...opsys.com>
To: Prashanth K <prashanth.k@....qualcomm.com>
CC: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Thinh Nguyen <Thinh.Nguyen@...opsys.com>,
        Bjorn Andersson <bjorn.andersson@....qualcomm.com>,
        Krishna Kurapati <krishna.kurapati@....qualcomm.com>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] usb: dwc3: qcom: Add shutdown handler

On Fri, Jul 25, 2025, Prashanth K wrote:
> Currently during system reboot, SMMU disables its translations
> while devices like USB may still be actively using DMA buffers.
> This can lead to NOC errors and system crashes due to invalid
> memory access.
> 
> Address this by adding a shutdown callback to dwc3-qcom, which
> ensures proper teardown of UDC stack and prevents DWC3 controller
> from accessing memory after SMMU translation is disabled. Reuse
> the existing remove callback for this purpose.
> 
> Signed-off-by: Prashanth K <prashanth.k@....qualcomm.com>
> ---
>  drivers/usb/dwc3/dwc3-qcom.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/usb/dwc3/dwc3-qcom.c b/drivers/usb/dwc3/dwc3-qcom.c
> index ca7e1c02773a..308360a32c93 100644
> --- a/drivers/usb/dwc3/dwc3-qcom.c
> +++ b/drivers/usb/dwc3/dwc3-qcom.c
> @@ -764,11 +764,14 @@ static void dwc3_qcom_remove(struct platform_device *pdev)
>  	struct dwc3 *dwc = platform_get_drvdata(pdev);
>  	struct dwc3_qcom *qcom = to_dwc3_qcom(dwc);
>  
> -	dwc3_core_remove(&qcom->dwc);
> +	if (pm_runtime_resume_and_get(qcom->dev) < 0)
> +		return;
>  
> +	dwc3_core_remove(&qcom->dwc);
>  	clk_bulk_disable_unprepare(qcom->num_clocks, qcom->clks);
> -
>  	dwc3_qcom_interconnect_exit(qcom);
> +
> +	pm_runtime_put_noidle(qcom->dev);
>  }
>  
>  static int dwc3_qcom_pm_suspend(struct device *dev)
> @@ -873,6 +876,7 @@ MODULE_DEVICE_TABLE(of, dwc3_qcom_of_match);
>  static struct platform_driver dwc3_qcom_driver = {
>  	.probe		= dwc3_qcom_probe,
>  	.remove		= dwc3_qcom_remove,
> +	.shutdown	= dwc3_qcom_remove,
>  	.driver		= {
>  		.name	= "dwc3-qcom",
>  		.pm	= pm_ptr(&dwc3_qcom_dev_pm_ops),
> -- 
> 2.25.1
> 

Acked-by: Thinh Nguyen <Thinh.Nguyen@...opsys.com>

BR,
Thinh