linux-kernel - Re: [PATCH] usb: Clear both buffers when clearing a control transfer TT buffer.

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Message-ID: <51CD9588.5010305@cogentembedded.com>
Date:	Fri, 28 Jun 2013 17:54:16 +0400
From:	Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
To:	William Gulland <wgulland@...gle.com>
CC:	Alan Stern <stern@...land.harvard.edu>,
	Sarah Sharp <sarah.a.sharp@...ux.intel.com>,
	Lan Tianyu <tianyu.lan@...el.com>,
	Ming Lei <ming.lei@...onical.com>, linux-usb@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] usb: Clear both buffers when clearing a control transfer
 TT buffer.

Hello.

On 28-06-2013 3:10, William Gulland wrote:

>      Control transfers have both IN and OUT (or SETUP) packets, so when
>      clearing TT buffers for a control transfer it's necessary to send
>      two HUB_CLEAR_TT_BUFFER requests to the hub.

> Signed-off-by: William Gulland <wgulland@...gle.com>
> ---
>   drivers/usb/core/hub.c | 9 +++++++++
>   1 file changed, 9 insertions(+)

> diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
> index feef935..868ad74 100644
> --- a/drivers/usb/core/hub.c
> +++ b/drivers/usb/core/hub.c
> @@ -668,6 +668,15 @@ resubmit:
>   static inline int
>   hub_clear_tt_buffer (struct usb_device *hdev, u16 devinfo, u16 tt)
>   {
> +	/* Need to clear both directions for control ep */
> +	if (((devinfo >> 11) & USB_ENDPOINT_XFERTYPE_MASK) ==
> +			USB_ENDPOINT_XFER_CONTROL) {
> +		int status = usb_control_msg(hdev, usb_sndctrlpipe(hdev, 0),
> +				HUB_CLEAR_TT_BUFFER, USB_RT_PORT,
> +				devinfo ^ 0x8000, tt, NULL, 0, 1000);

    Could you use consistent indentation style with the below call?
Also, empty line wouldn't hurt after declaration...

> +		if (status)
> +			return status;
> +	}
>   	return usb_control_msg(hdev, usb_sndctrlpipe(hdev, 0),
>   			       HUB_CLEAR_TT_BUFFER, USB_RT_PORT, devinfo,
>   			       tt, NULL, 0, 1000);

WBR, Sergei

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