linux-kernel - About TRB_TO_EP

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Message-ID: <0C18FE92A7765D4EB9EE5D38D86A563A019660C8@SHSMSX103.ccr.corp.intel.com>
Date:	Mon, 5 Aug 2013 08:07:25 +0000
From:	"Du, ChangbinX" <changbinx.du@...el.com>
To:	"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>,
	"balbi@...com" <balbi@...com>,
	"sarah.a.sharp@...uxfoundation.org" 
	<sarah.a.sharp@...uxfoundation.org>, "Wu, Hao" <hao.wu@...el.com>,
	"Tang, Jianqiang" <jianqiang.tang@...el.com>,
	"Zhuang, Jin Can" <jin.can.zhuang@...el.com>,
	"Huang, Xiaochao" <xiaochao.huang@...el.com>
Subject: About TRB_TO_EP_INDEX() macro using

Recently when I check xHCI code, find that some functions try to get EP index 
from a Command Completion Event TRB via TRB_TO_EP_INDEX() macro.

This is totally wrong. The macro definition is:

	#define TRB_TO_EP_INDEX(p)		((((p) & (0x1f << 16)) >> 16) - 1)

TRB_TO_EP_INDEX only applies to Transfer Event TRB. But for Command 
Completion Event TRB, there is no Endpoint ID field. So, we cannot directly 
get EP index from these TRBs, but we can find it by the TRB Pointer.

Here list two functions for you to check:
	handle_stopped_endpoint()
	handle_reset_ep_completion()

Regards & Thanks!
Changbin


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