Re: [PATCH v2] usb: chipidea: add loop timeout for hw_ep_set_halt()

Greg Kroah-Hartman
2021-08-26T11:17:37Z

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@rtst.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