Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752596AbbKQK3G (ORCPT ); Tue, 17 Nov 2015 05:29:06 -0500 Received: from mx5.ptsecurity.com ([45.58.112.35]:11667 "EHLO mx5.ptsecurity.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750710AbbKQK3E convert rfc822-to-8bit (ORCPT ); Tue, 17 Nov 2015 05:29:04 -0500 From: Dmitry Malkin To: Lu Baolu , "linux-kernel@vger.kernel.org" , "linux-usb@vger.kernel.org" Subject: Re: [PATCH v3 04/12] usb: xhci: dbc: add support for Intel xHCI dbc quirk Thread-Topic: [PATCH v3 04/12] usb: xhci: dbc: add support for Intel xHCI dbc quirk Thread-Index: AQHRHhrJDg8saylWaUy5AlaiIDE6P56aEkjDgAOpcQCAAkwjeQ== Date: Tue, 17 Nov 2015 10:28:59 +0000 Message-ID: <1447756139531.72345@ptsecurity.com> References: <1447425637180.84662@ptsecurity.com> <1447428842332.88038@ptsecurity.com>,<56493D02.8020204@linux.intel.com> In-Reply-To: <56493D02.8020204@linux.intel.com> Accept-Language: en-US, ru-RU Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1402 Lines: 36 On Mon, 16 Nov 2015 10:18:42 +0800, Lu Baolu wrote: > This quirk works as well if debug host doesn't have DBC. I didn't try a > DBC-capable debug host yet. Hi, I went through it again, with your v3 patch series on top of vanilla v4.3.0. Two targets, one host, all with Intel chipset (XHCI device 0:14.0 with VID:8086). Targets DIDs are 9c31 (8-series chipset) and 9d2f (100-series chipset). Host DID is 8c31 (8-series). I can only further confirm my previous observations. The host cannot see the target (there is no debug device) at all, until I manually re-plug a debug cable. Cable plugged in, prior to starting the target. I think that trying a Hot Reset for all disconnected USB 3.0 ports on the debug target *just before* setting DCE bit is inherently racy. What if the number of disconnected ports changes or if someone will insert a print statement or refactors your code? Also sending TS2 to the debug host port will either: - get dropped by its hub as unsupported upstream request, or - get ignored due to SS.Inactive port state Could you explain what exactly you workaround does at the low level? -- with best regards, Dmitry Malkin -- 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/