linux-kernel - Re: [PATCH 5/5] usb: dwc3: gadget: Increase DWC3 controller halt timeout

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Date:   Sat, 9 Jul 2022 01:47:50 +0000
From:   Thinh Nguyen <Thinh.Nguyen@...opsys.com>
To:     Wesley Cheng <quic_wcheng@...cinc.com>,
        "balbi@...nel.org" <balbi@...nel.org>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        Thinh Nguyen <Thinh.Nguyen@...opsys.com>,
        "quic_jackp@...cinc.com" <quic_jackp@...cinc.com>
Subject: Re: [PATCH 5/5] usb: dwc3: gadget: Increase DWC3 controller halt
 timeout

On 7/8/2022, Wesley Cheng wrote:
> Since EP0 transactions need to be completed before the controller halt
> sequence is finished, this may take some time depending on the host and the
> enabled functions.  Increase the controller halt timeout, so that we give
> the controller sufficient time to handle EP0 transfers.
>
> Signed-off-by: Wesley Cheng <quic_wcheng@...cinc.com>
> ---
>   drivers/usb/dwc3/gadget.c | 1 +
>   1 file changed, 1 insertion(+)
>
> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> index fba2797ad9ae..a5c0e39bd002 100644
> --- a/drivers/usb/dwc3/gadget.c
> +++ b/drivers/usb/dwc3/gadget.c
> @@ -2487,6 +2487,7 @@ static int dwc3_gadget_run_stop(struct dwc3 *dwc, int is_on, int suspend)
>   	do {
>   		reg = dwc3_readl(dwc->regs, DWC3_DSTS);
>   		reg &= DWC3_DSTS_DEVCTRLHLT;
> +		msleep(1);

I think it makes more sense to msleep() first before reading the register.

Thanks,
Thinh

>   	} while (--timeout && !(!is_on ^ !reg));
>   
>   	if (!timeout)