linux-kernel - Re: [PATCH v2] usb: chipidea: add loop timeout for hw_ep_set

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Message-ID: <YSd4Sp25RtT1b+rm@kroah.com>
Date:   Thu, 26 Aug 2021 13:17:30 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Jeaho Hwang <jhhwang@...t.co.kr>
Cc:     Peter Chen <peter.chen@...nel.org>, linux-usb@...r.kernel.org,
        linux-kernel@...r.kernel.org, team-linux@...t.co.kr,
        mkbyeon@...lectric.co.kr, khchoib@...lectric.co.kr
Subject: Re: [PATCH v2] usb: chipidea: add loop timeout for hw_ep_set_halt()

On Tue, Aug 17, 2021 at 03:43:53PM +0900, Jeaho Hwang wrote:
> If ctrl EP priming is failed (very rare case in standard linux),
> hw_ep_set_halt goes infinite loop. waiting 100 times was enough
> for zynq7000.
> 
> Signed-off-by: Jeaho Hwang <jhhwang@...t.co.kr>
> 
> diff --git a/drivers/usb/chipidea/udc.c b/drivers/usb/chipidea/udc.c
> index 8834ca613721..d73fadb18f32 100644
> --- a/drivers/usb/chipidea/udc.c
> +++ b/drivers/usb/chipidea/udc.c
> @@ -209,6 +209,9 @@ static int hw_ep_prime(struct ci_hdrc *ci, int num, int dir, int is_ctrl)
>  	return 0;
>  }
>  
> +/* enough for zynq7000 evaluation board */
> +#define HW_EP_SET_HALT_COUNT_MAX 100
> +
>  /**
>   * hw_ep_set_halt: configures ep halt & resets data toggle after clear (execute
>   *                 without interruption)
> @@ -221,6 +224,7 @@ static int hw_ep_prime(struct ci_hdrc *ci, int num, int dir, int is_ctrl)
>   */
>  static int hw_ep_set_halt(struct ci_hdrc *ci, int num, int dir, int value)
>  {
> +	int count = HW_EP_SET_HALT_COUNT_MAX;
>  	if (value != 0 && value != 1)

You need a blank line after "int count..."


>  		return -EINVAL;
>  
> @@ -232,9 +236,9 @@ static int hw_ep_set_halt(struct ci_hdrc *ci, int num, int dir, int value)
>  		/* data toggle - reserved for EP0 but it's in ESS */
>  		hw_write(ci, reg, mask_xs|mask_xr,
>  			  value ? mask_xs : mask_xr);
> -	} while (value != hw_ep_get_halt(ci, num, dir));
> +	} while (value != hw_ep_get_halt(ci, num, dir) && --count > 0);
>  
> -	return 0;
> +	return count ? 0 : -EAGAIN;

Please spell this out:
	if (count)
		return 0;
	return -EAGAIN;

And will the caller properly handle this?

thanks,

greg k-h