From mboxrd@z Thu Jan 1 00:00:00 1970 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 314B5C46467 for ; Wed, 11 Jan 2023 11:42:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232384AbjAKLmn (ORCPT ); Wed, 11 Jan 2023 06:42:43 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41492 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233799AbjAKLmR (ORCPT ); Wed, 11 Jan 2023 06:42:17 -0500 Received: from mail-pj1-x102d.google.com (mail-pj1-x102d.google.com [IPv6:2607:f8b0:4864:20::102d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 10A6F1A202 for ; Wed, 11 Jan 2023 03:41:11 -0800 (PST) Received: by mail-pj1-x102d.google.com with SMTP id z9-20020a17090a468900b00226b6e7aeeaso16842873pjf.1 for ; Wed, 11 Jan 2023 03:41:11 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=WGn0PbiFymHKMcNjUGWXoioOm7PfQt5MHEJvVchVE4s=; b=vQORdR6YtP3qXos2Sq8ad45eAuhZXsCz27JZRFq3fTkPUXkp5Yuamn7iSF5xo0dKGc t90Ik+2YovehtVfbbRiqAIdxkSlRwTBkv92uP04k+6eP3C9gcOT6KWXx1rqlyXXBqzyJ qg8VPMI1OoyEEiZ6WFsH8Mbm5Wg/KqmcxVXAsJZHcIfxOYG+vyjnDYHmUESLV2OmRu5w ikS762lJND84NQ7iuWObM/GJcxkIUARS69OiB2vl9WSqx8xelhQyYHLmjndn3feuyGYo FeANEJ6vdh6JQDoqWCasmnsG495/yALGi2GJY3CgJONvLwpLvfc6iVPin0b0eUrraybV GBcw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=WGn0PbiFymHKMcNjUGWXoioOm7PfQt5MHEJvVchVE4s=; b=6bI0mo+m4Jx1LjXoTzzuMVHOdH0KSFm3YXsm7K2Y4+9EqrikHI1qV9IkHk5eqhmprk SFAUgCHphFTofrOoesJC8cMnJVJc8tzcAQWzY+u7d+eoKwZSiFSXG0qCvktY3mB7AT+X F72znooE1x6U2Hv3bK6Vdyy1c+1f3/vhaw9yOs/ALx6j7ZU9gYISIbDfXSneZL9xMANM w7UV70srh+WhyA4xK6Jq1NyhQCSjUsHm2WNmafaVrH9oN9oTRwT/1uyvO07TxNeJGPi+ a8ZtoRIb/N6cMKm3ZVGQNUcdvDM95gFcPXlCWBs/6rIE2Ni/P0iMTa5TXT8NBtFmuBoB WstA== X-Gm-Message-State: AFqh2kqxp2fU4PGiDHECelWXNF+h+vQHfapNXky3yBnnoQl8/knFU7TT ovdcmmMy4AyY6iTeMB+gXCSF X-Google-Smtp-Source: AMrXdXuBl2ZhAZQRvCvILyuORpqz/vseZxHZTIPCgKgEyfzzOBe1BUnhX7xv1+dj9b0WEizfhn4REA== X-Received: by 2002:a17:902:e805:b0:192:4b3e:9f8e with SMTP id u5-20020a170902e80500b001924b3e9f8emr87640938plg.36.1673437270953; Wed, 11 Jan 2023 03:41:10 -0800 (PST) Received: from localhost.localdomain ([117.217.177.1]) by smtp.gmail.com with ESMTPSA id u14-20020a170902e5ce00b0018958a913a2sm9942688plf.223.2023.01.11.03.41.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 11 Jan 2023 03:41:10 -0800 (PST) From: Manivannan Sadhasivam To: kishon@kernel.org, lpieralisi@kernel.org, bhelgaas@google.com Cc: linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, kw@linux.com, robh@kernel.org, vidyas@nvidia.com, vigneshr@ti.com, Manivannan Sadhasivam Subject: [RESEND v4 0/5] PCI: endpoint: Rework the EPC to EPF notification Date: Wed, 11 Jan 2023 17:10:54 +0530 Message-Id: <20230111114059.6553-1-manivannan.sadhasivam@linaro.org> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org Hello, During the review of the patch that fixes DBI access in PCI EP, Rob suggested [1] using a fixed interface for passing the events from EPC to EPF instead of the in-kernel notifiers. This series introduces a simple callback based mechanism for passing the events from EPC to EPF. This interface is chosen for satisfying the below requirements: 1. The notification has to reach the EPF drivers without any additional latency. 2. The context of the caller (EPC) needs to be preserved while passing the notifications. With the existing notifier mechanism, the 1st case can be satisfied since notifiers aren't adding any huge overhead. But the 2nd case is clearly not satisfied, because the current atomic notifiers forces the EPF notification context to be atomic even though the caller (EPC) may not be in atomic context. In the notification function, the EPF drivers are required to call several EPC APIs that might sleep and this triggers a sleeping in atomic bug during runtime. The above issue could be fixed by using a blocking notifier instead of atomic, but that proposal was not accepted either [2]. So instead of working around the issues within the notifiers, let's get rid of it and use the callback mechanism. NOTE: DRA7xx and TEGRA194 drivers are only compile tested. Testing this series on the real platforms is greatly appreciated. Thanks, Mani [1] https://lore.kernel.org/all/20220802072426.GA2494@thinkpad/T/#mfa3a5b3a9694798a562c36b228f595b6a571477d [2] https://lore.kernel.org/all/20220228055240.24774-1-manivannan.sadhasivam@linaro.org Changes in v4: * Added check for the presence of event_ops before involing the callbacks (Kishon) * Added return with IRQ_WAKE_THREAD when link_up event is found in the hard irq handler of tegra194 driver (Vidya) * Collected review tags Changes in v3: * As Kishon spotted, fixed the DRA7xx driver and also the TEGRA194 driver to call the LINK_UP callback in threaded IRQ handler. Changes in v2: * Introduced a new "list_lock" for protecting the epc->pci_epf list and used it in the callback mechanism. Manivannan Sadhasivam (5): PCI: dra7xx: Use threaded IRQ handler for "dra7xx-pcie-main" IRQ PCI: tegra194: Move dw_pcie_ep_linkup() to threaded IRQ handler PCI: endpoint: Use a separate lock for protecting epc->pci_epf list PCI: endpoint: Use callback mechanism for passing events from EPC to EPF PCI: endpoint: Use link_up() callback in place of LINK_UP notifier drivers/pci/controller/dwc/pci-dra7xx.c | 2 +- drivers/pci/controller/dwc/pcie-tegra194.c | 9 ++++- drivers/pci/endpoint/functions/pci-epf-test.c | 38 ++++++------------- drivers/pci/endpoint/pci-epc-core.c | 32 ++++++++++++---- include/linux/pci-epc.h | 10 +---- include/linux/pci-epf.h | 19 ++++++---- 6 files changed, 59 insertions(+), 51 deletions(-) -- 2.25.1