Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759434Ab0KRQGl (ORCPT ); Thu, 18 Nov 2010 11:06:41 -0500 Received: from iolanthe.rowland.org ([192.131.102.54]:37862 "HELO iolanthe.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1759404Ab0KRQGj (ORCPT ); Thu, 18 Nov 2010 11:06:39 -0500 Date: Thu, 18 Nov 2010 11:06:37 -0500 (EST) From: Alan Stern X-X-Sender: stern@iolanthe.rowland.org To: Tatyana Brokhman cc: gregkh@suse.de, , , David Brownell , Subject: Re: [PATCH v6] usb: Adding SuperSpeed support to dummy_hcd In-Reply-To: <1290085052-4977-1-git-send-email-tlinder@codeaurora.org> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1324 Lines: 34 On Thu, 18 Nov 2010, Tatyana Brokhman wrote: > USB 3.0 hub includes 2 hubs - HS and SS ones. > Thus, when dummy_hcd enabled it will register 2 root hubs (SS and HS). Hmm. A quick comparison with the original source shows that you neglected to add code for SuperSpeed transfers to periodic_bytes() and show_urb(). > @@ -1352,6 +1544,9 @@ static void dummy_timer (unsigned long _dum) > case USB_SPEED_HIGH: > total = 512/*bytes*/ * 13/*packets*/ * 8/*uframes*/; > break; > + case USB_SPEED_SUPER: > + total = 400 << 20; /* 400MB = 400*(2^20) bytes */ > + break; Somehow I doubt that SuperSpeed USB, quick though it is, can transfer 400 MB in one millisecond. Where did you get that number from? I can't find the appropriate table in the USB-3.0 spec (it might not be there at all), but with a bus transfer rate of 500 million bytes/s it seems clear that you can't transfer more than 500000 bytes per frame. The actual limit must be lower than that, maybe something like 1024 bytes/packet * 60 packets/uframe * 8 uframes/frame = 491520 bytes/frame. Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/