Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756168Ab3H2SGe (ORCPT ); Thu, 29 Aug 2013 14:06:34 -0400 Received: from mail-ob0-f171.google.com ([209.85.214.171]:61550 "EHLO mail-ob0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756032Ab3H2SGb (ORCPT ); Thu, 29 Aug 2013 14:06:31 -0400 MIME-Version: 1.0 In-Reply-To: <20130829171852.GB5538@xanatos> References: <20130821184042.GC3577@xanatos> <20130822004514.GB19747@xanatos> <20130826191411.GG5112@xanatos> <20130828215142.GJ26483@xanatos> <20130829171852.GB5538@xanatos> Date: Thu, 29 Aug 2013 11:06:30 -0700 X-Google-Sender-Auth: tfp-mmn-NfS24E0-mgMYGqrw-G4 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" , Josh Triplett 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: 1729 Lines: 34 > If you take a look at Table > 13: BESL/HIRD Encoding from the xHCI spec version including errata to > 08/14/2012 Could you please provide a link to that errata? I still cannot find it... but from your explanation, that design decision sounds pretty horrible. Why didn't they just choose not to set old HLC flag in BESL controllers? Seems like the only purpose it provides there is to make old drivers break. Anyway, looks like we are stuck with it now, and need to deal with those mislabeled DWC3 versions. I agree with you that we should blacklist instead of whitelist, but I don't think the device tree is the best place to put that... we would have to figure out the exact DWC3 version for every processor/SoC dtsi file to determine if they are affected, and remember to keep that up to date as we added more. I would instead propose to check for the revision register directly in the DWC3 stack. I think I could add a little check to dwc3_host_init() and hack the quirk bit into the newly created XHCI controller instance if required. However, I only have an old (unaffected) 1.85 controller for testing, so I would need Synopsys to provide me with the exact revision numbers affected (as read from the register) and to test the change for us. Also, do we want to make it an XHCI_DISABLE_USB2_LPM or a XHCI_FORCE_USB2_BESL quirk? Assuming their BESL implementation is otherwise correct except for omitting that bit, the latter one should make those controllers work better. -- 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/