From patchwork Tue Aug 25 17:13:03 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Jean Delvare X-Patchwork-Id: 1351176 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=23.128.96.18; helo=vger.kernel.org; envelope-from=linux-i2c-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=suse.de Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 4BbbDG2brKz9sTY for ; Wed, 26 Aug 2020 03:13:18 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726119AbgHYRNM convert rfc822-to-8bit (ORCPT ); Tue, 25 Aug 2020 13:13:12 -0400 Received: from mx2.suse.de ([195.135.220.15]:34518 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726432AbgHYRNG (ORCPT ); Tue, 25 Aug 2020 13:13:06 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 2A0C1AE68; Tue, 25 Aug 2020 17:13:35 +0000 (UTC) Date: Tue, 25 Aug 2020 19:13:03 +0200 From: Jean Delvare To: Linux I2C Cc: Volker =?utf-8?q?R=C3=BCmelin?= , Bjorn Helgaas , Vaibhav Gupta Subject: [PATCH] i2c: i801: Fix resume bug Message-ID: <20200825191303.4a258073@endymion> Organization: SUSE Linux X-Mailer: Claws Mail 3.17.4 (GTK+ 2.24.32; x86_64-suse-linux-gnu) MIME-Version: 1.0 Sender: linux-i2c-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-i2c@vger.kernel.org From: Volker Rümelin On suspend the original host configuration gets restored. The resume routine has to undo this, otherwise the SMBus master may be left in disabled state or in i2c mode. [JD: Rebased on v5.8, simplified a condition.] Signed-off-by: Volker Rümelin Signed-off-by: Jean Delvare --- I noticed this bug in a QEMU x86_64 q35 VM booted with OVMF. OVMF doesn't initialize the SMBus master. After 1s of SMBus inactivity autosuspend disables the SMBus master. To reproduce please note QEMU's ICH9 SMBus emulation does not handle interrupts and it's necessary to pass the parameter disable_features=0x10 to the i2c_i801 driver. Note from JD: I can't test this. drivers/i2c/busses/i2c-i801.c | 21 ++++++++++++++------- 1 file changed, 14 insertions(+), 7 deletions(-) --- linux-5.8.orig/drivers/i2c/busses/i2c-i801.c 2020-08-25 11:54:30.371682962 +0200 +++ linux-5.8/drivers/i2c/busses/i2c-i801.c 2020-08-25 14:06:06.168116285 +0200 @@ -1709,6 +1709,13 @@ static inline int i801_acpi_probe(struct static inline void i801_acpi_remove(struct i801_priv *priv) { } #endif +static unsigned char i801_setup_hstcfg(unsigned char hstcfg) +{ + hstcfg &= ~SMBHSTCFG_I2C_EN; /* SMBus timing */ + hstcfg |= SMBHSTCFG_HST_EN; + return hstcfg; +} + static int i801_probe(struct pci_dev *dev, const struct pci_device_id *id) { unsigned char temp; @@ -1830,13 +1837,10 @@ static int i801_probe(struct pci_dev *de return err; } - pci_read_config_byte(priv->pci_dev, SMBHSTCFG, &temp); - priv->original_hstcfg = temp; - temp &= ~SMBHSTCFG_I2C_EN; /* SMBus timing */ - if (!(temp & SMBHSTCFG_HST_EN)) { + pci_read_config_byte(priv->pci_dev, SMBHSTCFG, &priv->original_hstcfg); + temp = i801_setup_hstcfg(priv->original_hstcfg); + if (!(priv->original_hstcfg & SMBHSTCFG_HST_EN)) dev_info(&dev->dev, "Enabling SMBus device\n"); - temp |= SMBHSTCFG_HST_EN; - } pci_write_config_byte(priv->pci_dev, SMBHSTCFG, temp); if (temp & SMBHSTCFG_SMB_SMI_EN) { @@ -1961,8 +1965,11 @@ static int i801_suspend(struct device *d static int i801_resume(struct device *dev) { - struct i801_priv *priv = dev_get_drvdata(dev); + struct pci_dev *pci_dev = to_pci_dev(dev); + struct i801_priv *priv = pci_get_drvdata(pci_dev); + unsigned char hstcfg = i801_setup_hstcfg(priv->original_hstcfg); + pci_write_config_byte(pci_dev, SMBHSTCFG, hstcfg); i801_enable_host_notify(&priv->adapter); return 0;