From patchwork Thu Feb 4 09:51:25 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mingchuang Qiao X-Patchwork-Id: 1435895 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-pci-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=mediatek.com header.i=@mediatek.com header.a=rsa-sha256 header.s=dk header.b=LfwqeIUU; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 4DWYkh0tbrz9sWl for ; Thu, 4 Feb 2021 20:52:44 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233597AbhBDJw0 (ORCPT ); Thu, 4 Feb 2021 04:52:26 -0500 Received: from mailgw02.mediatek.com ([1.203.163.81]:51312 "EHLO mailgw02.mediatek.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S235292AbhBDJwZ (ORCPT ); Thu, 4 Feb 2021 04:52:25 -0500 X-UUID: aae8768ba5b347539e6247ef73a9929e-20210204 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=mediatek.com; s=dk; h=Content-Transfer-Encoding:Content-Type:MIME-Version:Message-ID:Date:Subject:CC:To:From; bh=yCGwEsEVjQoUIZ8It18p5vUYxvCyrioMe/9PFTM4Wv8=; b=LfwqeIUU6kyKxpCCLwDesrEgvv/2Asn8gUZGGu7/gxLNhQUDM2APTpGKI0tHb3b8zWl86Sqxzzfd5B2S8Zhb6ZsABw+HqMs2WHojnQunYXmETTqgy2Lw+zvtvQhi5TyNdm0PLo+WMCjjxeJaQ2yZo0SCpbSlmbhVtOI+grAwXDU=; X-UUID: aae8768ba5b347539e6247ef73a9929e-20210204 Received: from mtkcas32.mediatek.inc [(172.27.4.253)] by mailgw02.mediatek.com (envelope-from ) (mailgw01.mediatek.com ESMTP with TLSv1.2 ECDHE-RSA-AES256-SHA384 256/256) with ESMTP id 1961543882; Thu, 04 Feb 2021 17:51:37 +0800 Received: from MTKCAS32.mediatek.inc (172.27.4.184) by MTKMBS31N1.mediatek.inc (172.27.4.69) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Thu, 4 Feb 2021 17:51:31 +0800 Received: from mcddlt001.mediatek.inc (10.19.240.15) by MTKCAS32.mediatek.inc (172.27.4.170) with Microsoft SMTP Server id 15.0.1497.2 via Frontend Transport; Thu, 4 Feb 2021 17:51:30 +0800 From: To: , CC: , , , , , , , , , , , Subject: [v4] PCI: Avoid unsync of LTR mechanism configuration Date: Thu, 4 Feb 2021 17:51:25 +0800 Message-ID: <20210204095125.9212-1-mingchuang.qiao@mediatek.com> X-Mailer: git-send-email 2.18.0 MIME-Version: 1.0 X-TM-SNTS-SMTP: A2F39DD1C52C3A4A4AADE6AFD365C93497CD1F4332D5C12853C645E0F0D636AF2000:8 X-MTK: N Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org From: Mingchuang Qiao In bus scan flow, the "LTR Mechanism Enable" bit of DEVCTL2 register is configured in pci_configure_ltr(). If device and bridge both support LTR mechanism, the "LTR Mechanism Enable" bit of device and bridge will be enabled in DEVCTL2 register. And pci_dev->ltr_path will be set as 1. If PCIe link goes down when device resets, the "LTR Mechanism Enable" bit of bridge will change to 0 according to PCIe r5.0, sec 7.5.3.16. However, the pci_dev->ltr_path value of bridge is still 1. For following conditions, check and re-configure "LTR Mechanism Enable" bit of bridge to make "LTR Mechanism Enable" bit match ltr_path value. -before configuring device's LTR for hot-remove/hot-add -before restoring device's DEVCTL2 register when restore device state Signed-off-by: Mingchuang Qiao Reviewed-by: Mika Westerberg --- changes of v4 -fix typo of commit message -rename: pci_reconfigure_bridge_ltr()->pci_bridge_reconfigure_ltr() changes of v3 -call pci_reconfigure_bridge_ltr() in probe.c changes of v2 -modify patch description -reconfigure bridge's LTR before restoring device DEVCTL2 register --- drivers/pci/pci.c | 25 +++++++++++++++++++++++++ drivers/pci/pci.h | 1 + drivers/pci/probe.c | 13 ++++++++++--- 3 files changed, 36 insertions(+), 3 deletions(-) diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index b9fecc25d213..6bf65d295331 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -1437,6 +1437,24 @@ static int pci_save_pcie_state(struct pci_dev *dev) return 0; } +void pci_bridge_reconfigure_ltr(struct pci_dev *dev) +{ +#ifdef CONFIG_PCIEASPM + struct pci_dev *bridge; + u32 ctl; + + bridge = pci_upstream_bridge(dev); + if (bridge && bridge->ltr_path) { + pcie_capability_read_dword(bridge, PCI_EXP_DEVCTL2, &ctl); + if (!(ctl & PCI_EXP_DEVCTL2_LTR_EN)) { + pci_dbg(bridge, "re-enabling LTR\n"); + pcie_capability_set_word(bridge, PCI_EXP_DEVCTL2, + PCI_EXP_DEVCTL2_LTR_EN); + } + } +#endif +} + static void pci_restore_pcie_state(struct pci_dev *dev) { int i = 0; @@ -1447,6 +1465,13 @@ static void pci_restore_pcie_state(struct pci_dev *dev) if (!save_state) return; + /* + * Downstream ports reset the LTR enable bit when link goes down. + * Check and re-configure the bit here before restoring device. + * PCIe r5.0, sec 7.5.3.16. + */ + pci_bridge_reconfigure_ltr(dev); + cap = (u16 *)&save_state->cap.data[0]; pcie_capability_write_word(dev, PCI_EXP_DEVCTL, cap[i++]); pcie_capability_write_word(dev, PCI_EXP_LNKCTL, cap[i++]); diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h index 5c59365092fa..b3a5e5287cb7 100644 --- a/drivers/pci/pci.h +++ b/drivers/pci/pci.h @@ -111,6 +111,7 @@ void pci_free_cap_save_buffers(struct pci_dev *dev); bool pci_bridge_d3_possible(struct pci_dev *dev); void pci_bridge_d3_update(struct pci_dev *dev); void pci_bridge_wait_for_secondary_bus(struct pci_dev *dev); +void pci_bridge_reconfigure_ltr(struct pci_dev *dev); static inline void pci_wakeup_event(struct pci_dev *dev) { diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c index 953f15abc850..ade055e9fb58 100644 --- a/drivers/pci/probe.c +++ b/drivers/pci/probe.c @@ -2132,9 +2132,16 @@ static void pci_configure_ltr(struct pci_dev *dev) * Complex and all intermediate Switches indicate support for LTR. * PCIe r4.0, sec 6.18. */ - if (pci_pcie_type(dev) == PCI_EXP_TYPE_ROOT_PORT || - ((bridge = pci_upstream_bridge(dev)) && - bridge->ltr_path)) { + if (pci_pcie_type(dev) == PCI_EXP_TYPE_ROOT_PORT) { + pcie_capability_set_word(dev, PCI_EXP_DEVCTL2, + PCI_EXP_DEVCTL2_LTR_EN); + dev->ltr_path = 1; + return; + } + + bridge = pci_upstream_bridge(dev); + if (bridge && bridge->ltr_path) { + pci_bridge_reconfigure_ltr(dev); pcie_capability_set_word(dev, PCI_EXP_DEVCTL2, PCI_EXP_DEVCTL2_LTR_EN); dev->ltr_path = 1;