Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755439Ab3H1XIP (ORCPT ); Wed, 28 Aug 2013 19:08:15 -0400 Received: from mail-ob0-f174.google.com ([209.85.214.174]:36318 "EHLO mail-ob0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753141Ab3H1XIN (ORCPT ); Wed, 28 Aug 2013 19:08:13 -0400 MIME-Version: 1.0 In-Reply-To: References: <1377040909-18428-1-git-send-email-jwerner@chromium.org> <20130821184042.GC3577@xanatos> <20130822004514.GB19747@xanatos> <20130826191411.GG5112@xanatos> <20130828215142.GJ26483@xanatos> Date: Wed, 28 Aug 2013 16:08:12 -0700 X-Google-Sender-Auth: -3afMmH4T4EAp5A32Oe0x6gwEyU Message-ID: Subject: Re: [PATCH] usb: xhci-plat: Enable USB 2.0 hardware LPM support for platform xHCs From: Julius Werner To: Sarah Sharp Cc: Julius Werner , Paul Zimmerman , LKML , "linux-usb@vger.kernel.org" , Greg Kroah-Hartman , Vincent Palatin , Benson Leung , Felipe Balbi , "mathias.nyman@linux.intel.com" Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 998 Lines: 17 > So the 2.41a has BESL support, but may not set the BLC flag. What > happens if we use the HIRD encoding instead? Will things break? It > seems like we would need to disable USB 2.0 LPM on that host all > together, if it expects BESL encoding, but advertises HIRD encoding. Wait a second, just for clarity: are you saying that BESL-capable controllers do not support the old HIRD mechanism and thus just break on non-BESL aware OSes? I would've assumed that they somehow notice if software doesn't write to the new register and automatically fall back to HIRD... it seems like a weird decision to break hardware backwards compatibility like that (after all, it would mean that Linux 3.10 and older would also break on LynxPoint systems right now). -- 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/