From nobody Thu Sep 11 14:15:26 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 03598C7EE23 for ; Sun, 11 Jun 2023 17:21:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233960AbjFKRVS (ORCPT ); Sun, 11 Jun 2023 13:21:18 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45510 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233888AbjFKRVN (ORCPT ); Sun, 11 Jun 2023 13:21:13 -0400 X-Greylist: delayed 92 seconds by postgrey-1.37 at lindbergh.monkeyblade.net; Sun, 11 Jun 2023 10:20:49 PDT Received: from angie.orcam.me.uk (angie.orcam.me.uk [78.133.224.34]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id E45F71700; Sun, 11 Jun 2023 10:20:48 -0700 (PDT) Received: by angie.orcam.me.uk (Postfix, from userid 500) id 4E8B29200C6; Sun, 11 Jun 2023 19:19:53 +0200 (CEST) Received: from localhost (localhost [127.0.0.1]) by angie.orcam.me.uk (Postfix) with ESMTP id 4858E9200B3; Sun, 11 Jun 2023 18:19:53 +0100 (BST) Date: Sun, 11 Jun 2023 18:19:53 +0100 (BST) From: "Maciej W. Rozycki" To: Bjorn Helgaas , Mahesh J Salgaonkar , Oliver O'Halloran , Michael Ellerman , Nicholas Piggin , Christophe Leroy , Saeed Mahameed , Leon Romanovsky , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni cc: Alex Williamson , Lukas Wunner , Mika Westerberg , Stefan Roese , Jim Wilson , David Abdurachmanov , =?UTF-8?Q?Pali_Roh=C3=A1r?= , linux-pci@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-rdma@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v9 10/14] PCI: Add support for polling DLLLA to `pcie_retrain_link' In-Reply-To: Message-ID: References: User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Let the caller of `pcie_retrain_link' specify whether they want to use=20 the LT bit or the DLLLA bit of the Link Status Register to determine if=20 link training has completed. It is up to the caller to verify whether=20 the use of the DLLLA bit, the implementation of which is optional, is=20 valid for the device requested. Signed-off-by: Maciej W. Rozycki --- New change in v9. --- drivers/pci/pci.c | 28 ++++++++++++++++++++-------- drivers/pci/pci.h | 2 +- drivers/pci/pcie/aspm.c | 2 +- 3 files changed, 22 insertions(+), 10 deletions(-) linux-pcie-retrain-link-use-lt.diff Index: linux-macro/drivers/pci/pci.c =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D --- linux-macro.orig/drivers/pci/pci.c +++ linux-macro/drivers/pci/pci.c @@ -4850,25 +4850,32 @@ static int pci_pm_reset(struct pci_dev * } =20 /** - * pcie_wait_for_link_status - Wait for link training end + * pcie_wait_for_link_status - Wait for link status change * @pdev: Device whose link to wait for. + * @use_lt: Use the LT bit if TRUE, or the DLLLA bit if FALSE. + * @active: Waiting for active or inactive? * - * Return TRUE if successful, or FALSE if training has not completed - * within PCIE_LINK_RETRAIN_TIMEOUT_MS milliseconds. + * Return TRUE if successful, or FALSE if status has not changed within + * PCIE_LINK_RETRAIN_TIMEOUT_MS milliseconds. */ -static bool pcie_wait_for_link_status(struct pci_dev *pdev) +static bool pcie_wait_for_link_status(struct pci_dev *pdev, + bool use_lt, bool active) { + u16 lnksta_mask, lnksta_match; unsigned long end_jiffies; u16 lnksta; =20 + lnksta_mask =3D use_lt ? PCI_EXP_LNKSTA_LT : PCI_EXP_LNKSTA_DLLLA; + lnksta_match =3D active ? lnksta_mask : 0; + end_jiffies =3D jiffies + msecs_to_jiffies(PCIE_LINK_RETRAIN_TIMEOUT_MS); do { pcie_capability_read_word(pdev, PCI_EXP_LNKSTA, &lnksta); - if (!(lnksta & PCI_EXP_LNKSTA_LT)) + if ((lnksta & lnksta_mask) =3D=3D lnksta_match) break; msleep(1); } while (time_before(jiffies, end_jiffies)); - return !(lnksta & PCI_EXP_LNKSTA_LT); + return (lnksta & lnksta_mask) =3D=3D lnksta_match; } =20 /** @@ -4937,10 +4944,15 @@ bool pcie_wait_for_link(struct pci_dev * /** * pcie_retrain_link - Request a link retrain and wait for it to complete * @pdev: Device whose link to retrain. + * @use_lt: Use the LT bit if TRUE, or the DLLLA bit if FALSE, for status. + * + * Retrain completion status is retrieved from the Link Status Register + * according to @use_lt. It is not verified whether the use of the DLLLA + * bit is valid. * * Return TRUE if successful, or FALSE if training has not completed. */ -bool pcie_retrain_link(struct pci_dev *pdev) +bool pcie_retrain_link(struct pci_dev *pdev, bool use_lt) { u16 lnkctl; =20 @@ -4957,7 +4969,7 @@ bool pcie_retrain_link(struct pci_dev *p pcie_capability_write_word(pdev, PCI_EXP_LNKCTL, lnkctl); } =20 - return pcie_wait_for_link_status(pdev); + return pcie_wait_for_link_status(pdev, use_lt, !use_lt); } =20 /* Index: linux-macro/drivers/pci/pci.h =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D --- linux-macro.orig/drivers/pci/pci.h +++ linux-macro/drivers/pci/pci.h @@ -561,7 +561,7 @@ pci_ers_result_t pcie_do_recovery(struct pci_ers_result_t (*reset_subordinates)(struct pci_dev *pdev)); =20 bool pcie_wait_for_link(struct pci_dev *pdev, bool active); -bool pcie_retrain_link(struct pci_dev *pdev); +bool pcie_retrain_link(struct pci_dev *pdev, bool use_lt); #ifdef CONFIG_PCIEASPM void pcie_aspm_init_link_state(struct pci_dev *pdev); void pcie_aspm_exit_link_state(struct pci_dev *pdev); Index: linux-macro/drivers/pci/pcie/aspm.c =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D --- linux-macro.orig/drivers/pci/pcie/aspm.c +++ linux-macro/drivers/pci/pcie/aspm.c @@ -257,7 +257,7 @@ static void pcie_aspm_configure_common_c reg16 &=3D ~PCI_EXP_LNKCTL_CCC; pcie_capability_write_word(parent, PCI_EXP_LNKCTL, reg16); =20 - if (pcie_retrain_link(link->pdev)) + if (pcie_retrain_link(link->pdev, true)) return; =20 /* Training failed. Restore common clock configurations */