From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751370AbdDAKH0 (ORCPT ); Sat, 1 Apr 2017 06:07:26 -0400 Received: from mail7.pr.hu ([87.242.0.7]:39681 "EHLO mail7.pr.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750948AbdDAKHX (ORCPT ); Sat, 1 Apr 2017 06:07:23 -0400 From: =?UTF-8?q?Zolt=C3=A1n=20B=C3=B6sz=C3=B6rm=C3=A9nyi?= To: linux-usb@vger.kernel.org, linux-watchdog@vger.kernel.org, linux-i2c@vger.kernel.org Cc: linux-kernel@vger.kernel.org, =?UTF-8?q?Zolt=C3=A1n=20B=C3=B6sz=C3=B6rm=C3=A9nyi?= Subject: [PATCH 0/3] Fix sp5100_tco watchdog driver regression Date: Sat, 1 Apr 2017 12:06:06 +0200 Message-Id: <20170401100609.9054-1-zboszor@pr.hu> X-Mailer: git-send-email 2.9.3 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Spam-Score: 1.3 (+) X-Scan-Signature: 64f8e9f229a86bfa7dbc82a3963c54b9 X-Spam-Tracer: backend.mail.pr.hu 1.3 20170401100644Z Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Three drivers are accessing the same I/O ports (0xcd6 / 0xcd7) on AMD SB800 based machines without synchronization or with excluding each other out: * the USB quirk for isochronous transfers on SB800 (no locking) * sp5100_tco (request_region) * i2c-piix4 (request_region) Historically, the sp5100_tco watchdog driver used request_region() for these I/O ports but an i2c-piix4 improvement for SB800 in Linux 4.4-rc4 also added a request_region() call. Because of this and the load order of these drivers, this caused a regression and the watchdog function became non-functional. The commit that caused the regression is: commit 2fee61d22e606fc99ade9079fda15fdee83ec33e Author: Christian Fetzer Date: Thu Nov 19 20:13:48 2015 +0100 i2c: piix4: Add support for multiplexed main adapter in SB800 I was informed by Guenter Roeck that the alternative, i.e. using request_muxed_region() can fail, either because of a resource allocation failure, which is quite possible with long uptimes, or because there are no guarantees that an as yet unknown driver would also use request_muxed_region() consistently. Because of this, a common mutex across these driver was chosen to synchronize I/O port accesses and request_region() calls are removed from both i2c-piix4 and sp5100_tco to make the code uniform. This patch series implements this and restores the watchdog function. Signed-off-by: Zoltán Böszörményi drivers/i2c/busses/i2c-piix4.c | 59 ++++++++++++-------------------------- drivers/usb/host/pci-quirks.c | 14 ++++++--- drivers/watchdog/sp5100_tco.c | 24 +++++++--------- drivers/watchdog/sp5100_tco.h | 10 ++++--- include/linux/sb800.h | 15 ++++++++++ 5 files changed, 61 insertions(+), 61 deletions(-)