From patchwork Sat Sep 17 12:03:09 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Maciej W. Rozycki" X-Patchwork-Id: 1678896 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@legolas.ozlabs.org Authentication-Results: legolas.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=2620:137:e000::1:20; helo=out1.vger.email; envelope-from=linux-pci-owner@vger.kernel.org; receiver=) Received: from out1.vger.email (out1.vger.email [IPv6:2620:137:e000::1:20]) by legolas.ozlabs.org (Postfix) with ESMTP id 4MV8j64xKKz1ync for ; Sat, 17 Sep 2022 22:03:22 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229626AbiIQMDT (ORCPT ); Sat, 17 Sep 2022 08:03:19 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56876 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229586AbiIQMDN (ORCPT ); Sat, 17 Sep 2022 08:03:13 -0400 Received: from angie.orcam.me.uk (angie.orcam.me.uk [IPv6:2001:4190:8020::34]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id E9064303FA for ; Sat, 17 Sep 2022 05:03:12 -0700 (PDT) Received: by angie.orcam.me.uk (Postfix, from userid 500) id 13F2192009C; Sat, 17 Sep 2022 14:03:10 +0200 (CEST) Received: from localhost (localhost [127.0.0.1]) by angie.orcam.me.uk (Postfix) with ESMTP id 0E49D92009B; Sat, 17 Sep 2022 13:03:10 +0100 (BST) Date: Sat, 17 Sep 2022 13:03:09 +0100 (BST) From: "Maciej W. Rozycki" To: Bjorn Helgaas cc: Stefan Roese , Jim Wilson , David Abdurachmanov , linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v5 1/5] PCI: Consistently report presence of PCIe link registers In-Reply-To: Message-ID: References: User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,SPF_HELO_NONE, SPF_NONE autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org Consistently with commit c8b303d0206b ("PCI: Remove PCIe Capability version checks") only consider the PCI Express capability's Link Control 2, etc. registers present if the Link Control register is. Before said commit with PCI Express capability versions higher than one all link registers used to be considered present, however starting from said commit Link Control, etc. original registers are only considered present in devices with links, but Link Control 2, etc. registers continue being considered always present even though likewise they are only present in devices with links. Fix the inconsistency then. Signed-off-by: Maciej W. Rozycki --- New change in v5. --- drivers/pci/access.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) linux-pcie-cap-has-lnkctl2.diff Index: linux-macro/drivers/pci/access.c =================================================================== --- linux-macro.orig/drivers/pci/access.c +++ linux-macro/drivers/pci/access.c @@ -350,6 +350,11 @@ bool pcie_cap_has_lnkctl(const struct pc type == PCI_EXP_TYPE_PCIE_BRIDGE; } +static inline bool pcie_cap_has_lnkctl2(const struct pci_dev *dev) +{ + return pcie_cap_has_lnkctl(dev) && pcie_cap_version(dev) > 1; +} + static inline bool pcie_cap_has_sltctl(const struct pci_dev *dev) { return pcie_downstream_port(dev) && @@ -390,10 +395,11 @@ static bool pcie_capability_reg_implemen return pcie_cap_has_rtctl(dev); case PCI_EXP_DEVCAP2: case PCI_EXP_DEVCTL2: + return pcie_cap_version(dev) > 1; case PCI_EXP_LNKCAP2: case PCI_EXP_LNKCTL2: case PCI_EXP_LNKSTA2: - return pcie_cap_version(dev) > 1; + return pcie_cap_has_lnkctl2(dev); default: return false; } From patchwork Sat Sep 17 12:03:14 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Maciej W. Rozycki" X-Patchwork-Id: 1678897 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@legolas.ozlabs.org Authentication-Results: legolas.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=2620:137:e000::1:20; helo=out1.vger.email; envelope-from=linux-pci-owner@vger.kernel.org; receiver=) Received: from out1.vger.email (out1.vger.email [IPv6:2620:137:e000::1:20]) by legolas.ozlabs.org (Postfix) with ESMTP id 4MV8jD4NN6z1ync for ; Sat, 17 Sep 2022 22:03:28 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229662AbiIQMD0 (ORCPT ); Sat, 17 Sep 2022 08:03:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56996 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229624AbiIQMDS (ORCPT ); Sat, 17 Sep 2022 08:03:18 -0400 Received: from angie.orcam.me.uk (angie.orcam.me.uk [IPv6:2001:4190:8020::34]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 6DB9039BA4 for ; Sat, 17 Sep 2022 05:03:17 -0700 (PDT) Received: by angie.orcam.me.uk (Postfix, from userid 500) id EE15F92009C; Sat, 17 Sep 2022 14:03:14 +0200 (CEST) Received: from localhost (localhost [127.0.0.1]) by angie.orcam.me.uk (Postfix) with ESMTP id E70C492009B; Sat, 17 Sep 2022 13:03:14 +0100 (BST) Date: Sat, 17 Sep 2022 13:03:14 +0100 (BST) From: "Maciej W. Rozycki" To: Bjorn Helgaas cc: Stefan Roese , Jim Wilson , David Abdurachmanov , linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v5 2/5] PCI: Export `pcie_cap_has_lnkctl2' In-Reply-To: Message-ID: References: User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,SPF_HELO_NONE, SPF_NONE autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org Export `pcie_cap_has_lnkctl2' for external use. Signed-off-by: Maciej W. Rozycki --- New change in v5. --- drivers/pci/access.c | 2 +- drivers/pci/pci.h | 1 + 2 files changed, 2 insertions(+), 1 deletion(-) linux-pcie-cap-has-lnkctl2-export.diff Index: linux-macro/drivers/pci/access.c =================================================================== --- linux-macro.orig/drivers/pci/access.c +++ linux-macro/drivers/pci/access.c @@ -350,7 +350,7 @@ bool pcie_cap_has_lnkctl(const struct pc type == PCI_EXP_TYPE_PCIE_BRIDGE; } -static inline bool pcie_cap_has_lnkctl2(const struct pci_dev *dev) +bool pcie_cap_has_lnkctl2(const struct pci_dev *dev) { return pcie_cap_has_lnkctl(dev) && pcie_cap_version(dev) > 1; } Index: linux-macro/drivers/pci/pci.h =================================================================== --- linux-macro.orig/drivers/pci/pci.h +++ linux-macro/drivers/pci/pci.h @@ -15,6 +15,7 @@ extern const unsigned char pcie_link_spe extern bool pci_early_dump; bool pcie_cap_has_lnkctl(const struct pci_dev *dev); +bool pcie_cap_has_lnkctl2(const struct pci_dev *dev); bool pcie_cap_has_rtctl(const struct pci_dev *dev); /* Functions internal to the PCI core code */ From patchwork Sat Sep 17 12:03:19 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Maciej W. Rozycki" X-Patchwork-Id: 1678898 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@legolas.ozlabs.org Authentication-Results: legolas.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=2620:137:e000::1:20; helo=out1.vger.email; envelope-from=linux-pci-owner@vger.kernel.org; receiver=) Received: from out1.vger.email (out1.vger.email [IPv6:2620:137:e000::1:20]) by legolas.ozlabs.org (Postfix) with ESMTP id 4MV8jQ5g9qz1ync for ; Sat, 17 Sep 2022 22:03:38 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229509AbiIQMDf (ORCPT ); Sat, 17 Sep 2022 08:03:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56890 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229568AbiIQMD3 (ORCPT ); Sat, 17 Sep 2022 08:03:29 -0400 Received: from angie.orcam.me.uk (angie.orcam.me.uk [IPv6:2001:4190:8020::34]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 767553A15A for ; Sat, 17 Sep 2022 05:03:22 -0700 (PDT) Received: by angie.orcam.me.uk (Postfix, from userid 500) id E39DC92009C; Sat, 17 Sep 2022 14:03:19 +0200 (CEST) Received: from localhost (localhost [127.0.0.1]) by angie.orcam.me.uk (Postfix) with ESMTP id DCEA292009B; Sat, 17 Sep 2022 13:03:19 +0100 (BST) Date: Sat, 17 Sep 2022 13:03:19 +0100 (BST) From: "Maciej W. Rozycki" To: Bjorn Helgaas cc: Stefan Roese , Jim Wilson , David Abdurachmanov , linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v5 3/5] PCI: Export PCI link retrain timeout In-Reply-To: Message-ID: References: User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,SPF_HELO_NONE, SPF_NONE autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org Rename LINK_RETRAIN_TIMEOUT to PCIE_LINK_RETRAIN_TIMEOUT and make it available via "pci.h" for PCI drivers to use. Signed-off-by: Maciej W. Rozycki --- New change in v5. --- drivers/pci/pci.h | 2 ++ drivers/pci/pcie/aspm.c | 4 +--- 2 files changed, 3 insertions(+), 3 deletions(-) linux-pcie-link-retrain-timeout.diff Index: linux-macro/drivers/pci/pci.h =================================================================== --- linux-macro.orig/drivers/pci/pci.h +++ linux-macro/drivers/pci/pci.h @@ -11,6 +11,8 @@ #define PCI_VSEC_ID_INTEL_TBT 0x1234 /* Thunderbolt */ +#define PCIE_LINK_RETRAIN_TIMEOUT HZ + extern const unsigned char pcie_link_speed[]; extern bool pci_early_dump; Index: linux-macro/drivers/pci/pcie/aspm.c =================================================================== --- linux-macro.orig/drivers/pci/pcie/aspm.c +++ linux-macro/drivers/pci/pcie/aspm.c @@ -89,8 +89,6 @@ static const char *policy_str[] = { [POLICY_POWER_SUPERSAVE] = "powersupersave" }; -#define LINK_RETRAIN_TIMEOUT HZ - /* * The L1 PM substate capability is only implemented in function 0 in a * multi function device. @@ -212,7 +210,7 @@ static bool pcie_retrain_link(struct pci } /* Wait for link training end. Break out after waiting for timeout */ - end_jiffies = jiffies + LINK_RETRAIN_TIMEOUT; + end_jiffies = jiffies + PCIE_LINK_RETRAIN_TIMEOUT; do { pcie_capability_read_word(parent, PCI_EXP_LNKSTA, ®16); if (!(reg16 & PCI_EXP_LNKSTA_LT)) From patchwork Sat Sep 17 12:03:23 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Maciej W. Rozycki" X-Patchwork-Id: 1678899 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@legolas.ozlabs.org Authentication-Results: legolas.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=2620:137:e000::1:20; helo=out1.vger.email; envelope-from=linux-pci-owner@vger.kernel.org; receiver=) Received: from out1.vger.email (out1.vger.email [IPv6:2620:137:e000::1:20]) by legolas.ozlabs.org (Postfix) with ESMTP id 4MV8jb3mvlz1ync for ; Sat, 17 Sep 2022 22:03:47 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229695AbiIQMDp (ORCPT ); Sat, 17 Sep 2022 08:03:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57134 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229587AbiIQMDd (ORCPT ); Sat, 17 Sep 2022 08:03:33 -0400 Received: from angie.orcam.me.uk (angie.orcam.me.uk [IPv6:2001:4190:8020::34]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 05BDC3A4B8 for ; Sat, 17 Sep 2022 05:03:28 -0700 (PDT) Received: by angie.orcam.me.uk (Postfix, from userid 500) id D92579200B3; Sat, 17 Sep 2022 14:03:23 +0200 (CEST) Received: from localhost (localhost [127.0.0.1]) by angie.orcam.me.uk (Postfix) with ESMTP id D600692009E; Sat, 17 Sep 2022 13:03:23 +0100 (BST) Date: Sat, 17 Sep 2022 13:03:23 +0100 (BST) From: "Maciej W. Rozycki" To: Bjorn Helgaas cc: Stefan Roese , Jim Wilson , David Abdurachmanov , linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v5 4/5] PCI: Execute `quirk_enable_clear_retrain_link' earlier In-Reply-To: Message-ID: References: User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,SPF_HELO_NONE, SPF_NONE autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org Make `quirk_enable_clear_retrain_link' `pci_fixup_early' so that any later fixups can rely on `clear_retrain_link' to have been already initialised. Signed-off-by: Maciej W. Rozycki --- New change in v5. --- drivers/pci/quirks.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) linux-pcie-clear-retrain-link-early.diff Index: linux-macro/drivers/pci/quirks.c =================================================================== --- linux-macro.orig/drivers/pci/quirks.c +++ linux-macro/drivers/pci/quirks.c @@ -2407,9 +2407,9 @@ static void quirk_enable_clear_retrain_l dev->clear_retrain_link = 1; pci_info(dev, "Enable PCIe Retrain Link quirk\n"); } -DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_PERICOM, 0xe110, quirk_enable_clear_retrain_link); -DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_PERICOM, 0xe111, quirk_enable_clear_retrain_link); -DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_PERICOM, 0xe130, quirk_enable_clear_retrain_link); +DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_PERICOM, 0xe110, quirk_enable_clear_retrain_link); +DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_PERICOM, 0xe111, quirk_enable_clear_retrain_link); +DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_PERICOM, 0xe130, quirk_enable_clear_retrain_link); static void fixup_rev1_53c810(struct pci_dev *dev) { From patchwork Sat Sep 17 12:03:38 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Maciej W. Rozycki" X-Patchwork-Id: 1678900 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@legolas.ozlabs.org Authentication-Results: legolas.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=2620:137:e000::1:20; helo=out1.vger.email; envelope-from=linux-pci-owner@vger.kernel.org; receiver=) Received: from out1.vger.email (out1.vger.email [IPv6:2620:137:e000::1:20]) by legolas.ozlabs.org (Postfix) with ESMTP id 4MV8jt4wYTz1ync for ; Sat, 17 Sep 2022 22:04:02 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229533AbiIQMEA (ORCPT ); Sat, 17 Sep 2022 08:04:00 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56874 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229685AbiIQMDm (ORCPT ); Sat, 17 Sep 2022 08:03:42 -0400 Received: from angie.orcam.me.uk (angie.orcam.me.uk [IPv6:2001:4190:8020::34]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 342833AB26; Sat, 17 Sep 2022 05:03:39 -0700 (PDT) Received: by angie.orcam.me.uk (Postfix, from userid 500) id 6F3F692009C; Sat, 17 Sep 2022 14:03:38 +0200 (CEST) Received: from localhost (localhost [127.0.0.1]) by angie.orcam.me.uk (Postfix) with ESMTP id 6858C92009B; Sat, 17 Sep 2022 13:03:38 +0100 (BST) Date: Sat, 17 Sep 2022 13:03:38 +0100 (BST) From: "Maciej W. Rozycki" To: Bjorn Helgaas cc: Stefan Roese , Jim Wilson , David Abdurachmanov , linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v5 5/5] PCI: Work around PCIe link training failures In-Reply-To: Message-ID: References: User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,SPF_HELO_NONE, SPF_NONE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org Attempt to handle cases such as with a downstream port of the ASMedia ASM2824 PCIe switch where link training never completes and the link continues switching between speeds indefinitely with the data link layer never reaching the active state. It has been observed with a downstream port of the ASMedia ASM2824 Gen 3 switch wired to the upstream port of the Pericom PI7C9X2G304 Gen 2 switch, using a Delock Riser Card PCI Express x1 > 2 x PCIe x1 device, P/N 41433, wired to a SiFive HiFive Unmatched board. In this setup the switches are supposed to negotiate the link speed of preferably 5.0GT/s, falling back to 2.5GT/s. Instead the link continues oscillating between the two speeds, at the rate of 34-35 times per second, with link training reported repeatedly active ~84% of the time. Forcibly limiting the target link speed to 2.5GT/s with the upstream ASM2824 device however makes the two switches communicate correctly. Removing the speed restriction afterwards makes the two devices switch to 5.0GT/s then. Make use of these observations then and detect the inability to train the link, by checking for the Data Link Layer Link Active status bit being off while the Link Bandwidth Management Status indicating that hardware has changed the link speed or width in an attempt to correct unreliable link operation. Restrict the speed to 2.5GT/s then with the Target Link Speed field, request a retrain and wait 200ms for the data link to go up. If this turns out successful, then lift the restriction, letting the devices negotiate a higher speed. Also check for a 2.5GT/s speed restriction the firmware may have already arranged and lift it too with ports of devices known to continue working afterwards, currently the ASM2824 only, that already report their data link being up. Signed-off-by: Maciej W. Rozycki Link: https://lore.kernel.org/lkml/alpine.DEB.2.21.2203022037020.56670@angie.orcam.me.uk/ Link: https://source.denx.de/u-boot/u-boot/-/commit/a398a51ccc68 --- Changes from v4: - Remove inclusion no longer needed. - Make the quirk generic based on probing device features rather than specific to the ASM2824 part only; take the Retrain Link bit erratum into account. - Still lift the 2.5GT/s speed restriction with the ASM2824 only. - Increase retrain timeout from 200ms to 1s (PCIE_LINK_RETRAIN_TIMEOUT). - Remove retrain success notification. - Use PCIe helpers rather than generic PCI functions throughout. - Trim down and update the wording of the change description for the switch from an ASM2824-specific to a generic fixup. Changes from v3: - Remove the entry for the ASM2824. Changes from v2: - Regenerate for 5.17-rc2 for a merge conflict. - Replace BUG_ON for a missing PCI Express capability with WARN_ON and an early return. Changes from v1: - Regenerate for a merge conflict. --- drivers/pci/quirks.c | 118 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 118 insertions(+) linux-pcie-asm2824-manual-retrain.diff Index: linux-macro/drivers/pci/quirks.c =================================================================== --- linux-macro.orig/drivers/pci/quirks.c +++ linux-macro/drivers/pci/quirks.c @@ -5956,3 +5956,121 @@ DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_I DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x56c0, aspm_l1_acceptable_latency); DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x56c1, aspm_l1_acceptable_latency); #endif + +/* + * Retrain the link of a downstream PCIe port by hand if necessary. + * + * This is needed at least where a downstream port of the ASMedia ASM2824 + * Gen 3 switch is wired to the upstream port of the Pericom PI7C9X2G304 + * Gen 2 switch, and observed with the Delock Riser Card PCI Express x1 > + * 2 x PCIe x1 device, P/N 41433, plugged into the SiFive HiFive Unmatched + * board. + * + * In such a configuration the switches are supposed to negotiate the link + * speed of preferably 5.0GT/s, falling back to 2.5GT/s. However the link + * continues switching between the two speeds indefinitely and the data + * link layer never reaches the active state, with link training reported + * repeatedly active ~84% of the time. Forcing the target link speed to + * 2.5GT/s with the upstream ASM2824 device makes the two switches talk to + * each other correctly however. And more interestingly retraining with a + * higher target link speed afterwards lets the two successfully negotiate + * 5.0GT/s. + * + * With the ASM2824 we can rely on the otherwise optional Data Link Layer + * Link Active status bit and in the failed link training scenario it will + * be off along with the Link Bandwidth Management Status indicating that + * hardware has changed the link speed or width in an attempt to correct + * unreliable link operation. For a port that has been left unconnected + * both bits will be clear. So use this information to detect the problem + * rather than polling the Link Training bit and watching out for flips or + * at least the active status. + * + * Since the exact nature of the problem isn't known and in principle this + * could trigger where an ASM2824 device is downstream rather upstream, + * apply this erratum workaround to any downstream ports as long as they + * support Link Active reporting and have the Link Control 2 register. + * Restrict the speed to 2.5GT/s then with the Target Link Speed field, + * request a retrain and wait 200ms for the data link to go up. + * + * If this turns out successful and we know by the Vendor:Device ID it is + * safe to do so, then lift the restriction, letting the devices negotiate + * a higher speed. Also check for a similar 2.5GT/s speed restriction the + * firmware may have already arranged and lift it with ports that already + * report their data link being up. + */ +static void pcie_downstream_link_retrain(struct pci_dev *dev) +{ + static const struct pci_device_id ids[] = { + { PCI_VDEVICE(ASMEDIA, 0x2824) }, /* ASMedia ASM2824 */ + {} + }; + u16 lnksta, lnkctl2; + u32 lnkcap; + + if (!pci_is_pcie(dev) || !pcie_downstream_port(dev) + || !pcie_cap_has_lnkctl2(dev)) + return; + + /* It's too early yet to use `dev->link_active_reporting'. */ + pcie_capability_read_dword(dev, PCI_EXP_LNKCAP, &lnkcap); + if (!(lnkcap & PCI_EXP_LNKCAP_DLLLARC)) + return; + + pcie_capability_read_word(dev, PCI_EXP_LNKCTL2, &lnkctl2); + pcie_capability_read_word(dev, PCI_EXP_LNKSTA, &lnksta); + if ((lnksta & (PCI_EXP_LNKSTA_LBMS | PCI_EXP_LNKSTA_DLLLA)) == + PCI_EXP_LNKSTA_LBMS) { + unsigned long timeout; + u16 lnkctl; + + pci_info(dev, "broken device, retraining non-functional downstream link at 2.5GT/s\n"); + + pcie_capability_read_word(dev, PCI_EXP_LNKCTL, &lnkctl); + lnkctl |= PCI_EXP_LNKCTL_RL; + lnkctl2 &= ~PCI_EXP_LNKCTL2_TLS; + lnkctl2 |= PCI_EXP_LNKCTL2_TLS_2_5GT; + pcie_capability_write_word(dev, PCI_EXP_LNKCTL2, lnkctl2); + pcie_capability_write_word(dev, PCI_EXP_LNKCTL, lnkctl); + /* + * Due to an erratum in some devices the Retrain Link bit + * needs to be cleared again manually to allow the link + * training to succeed. + */ + lnkctl &= ~PCI_EXP_LNKCTL_RL; + if (dev->clear_retrain_link) + pcie_capability_write_word(dev, PCI_EXP_LNKCTL, + lnkctl); + + timeout = jiffies + PCIE_LINK_RETRAIN_TIMEOUT; + do { + pcie_capability_read_word(dev, PCI_EXP_LNKSTA, + &lnksta); + if (lnksta & PCI_EXP_LNKSTA_DLLLA) + break; + usleep_range(10000, 20000); + } while (time_before(jiffies, timeout)); + + if (!(lnksta & PCI_EXP_LNKSTA_DLLLA)) { + pci_info(dev, "retraining failed\n"); + return; + } + } + + if ((lnksta & PCI_EXP_LNKSTA_DLLLA) && + (lnkctl2 & PCI_EXP_LNKCTL2_TLS) == PCI_EXP_LNKCTL2_TLS_2_5GT && + pci_match_id(ids, dev)) { + u16 lnkctl; + + pci_info(dev, "removing 2.5GT/s downstream link speed restriction\n"); + pcie_capability_read_word(dev, PCI_EXP_LNKCTL, &lnkctl); + lnkctl |= PCI_EXP_LNKCTL_RL; + lnkctl2 &= ~PCI_EXP_LNKCTL2_TLS; + lnkctl2 |= lnkcap & PCI_EXP_LNKCAP_SLS; + pcie_capability_write_word(dev, PCI_EXP_LNKCTL2, lnkctl2); + pcie_capability_write_word(dev, PCI_EXP_LNKCTL, lnkctl); + } +} +DECLARE_PCI_FIXUP_HEADER(PCI_ANY_ID, PCI_ANY_ID, + pcie_downstream_link_retrain); +DECLARE_PCI_FIXUP_RESUME_EARLY(PCI_ANY_ID, PCI_ANY_ID, + pcie_downstream_link_retrain);