Return-path: Received: from mail-bw0-f46.google.com ([209.85.214.46]:53306 "EHLO mail-bw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751542Ab0GMTQE (ORCPT ); Tue, 13 Jul 2010 15:16:04 -0400 Received: by bwz1 with SMTP id 1so483454bwz.19 for ; Tue, 13 Jul 2010 12:16:03 -0700 (PDT) From: Helmut Schaa To: Ivo Van Doorn Subject: Re: Rate control & USB Date: Tue, 13 Jul 2010 21:15:16 +0200 Cc: "linux-wireless" , Johannes Berg , Felix Fietkau References: <201007122114.09571.helmut.schaa@googlemail.com> In-Reply-To: MIME-Version: 1.0 Content-Type: Text/Plain; charset="us-ascii" Message-Id: <201007132115.16101.helmut.schaa@googlemail.com> Sender: linux-wireless-owner@vger.kernel.org List-ID: Am Dienstag 13 Juli 2010 schrieb Ivo Van Doorn: > On Mon, Jul 12, 2010 at 9:14 PM, Helmut Schaa > wrote: > > Am Montag 12 Juli 2010 schrieb Ivo Van Doorn: > >> I am currently looking into the old problem of the mac80211 rate > >> control algorithms > >> and USB devices. The Ralink USB devices (and as far as I know, the > >> other USB devices > >> as well), do not work well with the PID and Minstrel algorithms. This > >> is caused by the > >> fact that USB devices do not report the TX status to mac80211. > > > > Ivo, do you know by any chance if the USB devices also have a TX_STA_FIFO > > register like the PCI variants? Does it contain useful data or just crap? > > Well I guess he has the registers (we don't have rt2870 specific specsheets, > but the register definitions from the original Ralink driver to > suggest the register > is there). However, even if it contains valid data, how do you want to match > the contents of that register with the sent frames in the queue? We could stuff a unique packet ID into the TXWI and the TX_STA_FIFO should contain the same ID alongside the TX status after the frame was processed by the hw. > And another downside, is that the above only applies to rt2800usb, and not > for rt73usb and rt2500usb, which neither have the TX status register, and were > replaced with statistics registers (which I want to read for the batch > TX status). Ok, that's a valid argument ... Helmut