From patchwork Tue Jan 24 07:11:53 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Manivannan Sadhasivam X-Patchwork-Id: 13113587 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 E21FBC38142 for ; Tue, 24 Jan 2023 07:12:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233354AbjAXHMW (ORCPT ); Tue, 24 Jan 2023 02:12:22 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45522 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233077AbjAXHMV (ORCPT ); Tue, 24 Jan 2023 02:12:21 -0500 Received: from mail-pl1-x635.google.com (mail-pl1-x635.google.com [IPv6:2607:f8b0:4864:20::635]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1ACD32DE5A for ; Mon, 23 Jan 2023 23:12:20 -0800 (PST) Received: by mail-pl1-x635.google.com with SMTP id p24so13850163plw.11 for ; Mon, 23 Jan 2023 23:12:20 -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=7v3vKH0OUQa3EkOREw3bJ+B1AKEzvWHCw7MB+vHd9t4=; b=ZJSVtuBM+BhRrNs+A16J+fidiLqSEIJPMS2kMxaVz2bmdHms1q36mXFxsQNLsoleJK O6iXXm00waWsaNuJYNPCn/UlhEcrzuT7lzfjNQ3XSjscM1VYmkbYhIcbSViY08bH6uDJ EFlEFyFUz6WTD+jM4FV5qsbIP/yeOpKqZbEbis5ukW/K5skZJi2E3eYtpJJ7fwqYgspd EGC7a/y2PzCSQygcfX3t3NvD6SjZvShZpko//uPvG/qA7olPKwoG1iDm4r8ZpdIlnbv5 F+V0B0Sk8poONvMIWht3ogYwciMwpBNi1sGiCJU3k6NuKb1kGyjGef3P2CDomr8k5oTk j3oQ== 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=7v3vKH0OUQa3EkOREw3bJ+B1AKEzvWHCw7MB+vHd9t4=; b=C09xff9a43HfcMXmqCbDbd2whpu4qRI4CSAVOmTkPQOKUaj/u4ZvscuLSrJn+yivnF wEN61BECndQ8fchMNTkzevb4NlAXYdaxhqL5Wu39IsXcBfol2VM9kXVx0SCbnDI7/zdU fUUNgkfGPBNGb+Y3vkt9d/gSaiS1Ydj+WR9n97EZ7fMNvhLPMiB6kmbipAOm0DqPRHOA 0v0D2SIiFj93i0c6SEVHwP4hGKQWjjQW1d9A+z2XICpbRDNdSp+QAkYEB9c45yr+2lBC MY2o0qhfleUGZ14K5IZNFYep2QBTV62lX2P92PHno1Z4JGq0A65aF2l59j998QrIkeIq YUvw== X-Gm-Message-State: AFqh2koZCoBu1KMW+3e5G9j2zstQU5sN1VHPRhlzEsPgTR35EygHfDpu w6MVb4px3k4yOjlHn9XGTneG X-Google-Smtp-Source: AMrXdXsW7QSNkm4uOigZ/myGZxmMqpOzvzzypL4fJeke5jbE8aqCHXJGUWDZeA4LkX4bcoYOSSQfsg== X-Received: by 2002:a17:90b:35c9:b0:229:8e0c:68b0 with SMTP id nb9-20020a17090b35c900b002298e0c68b0mr29172185pjb.19.1674544339457; Mon, 23 Jan 2023 23:12:19 -0800 (PST) Received: from localhost.localdomain ([117.193.209.165]) by smtp.gmail.com with ESMTPSA id 7-20020a17090a174700b00219220edf0dsm736041pjm.48.2023.01.23.23.12.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 23 Jan 2023 23:12:18 -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: [PATCH v5 0/5] PCI: endpoint: Rework the EPC to EPF notification Date: Tue, 24 Jan 2023 12:41:53 +0530 Message-Id: <20230124071158.5503-1-manivannan.sadhasivam@linaro.org> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 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 v5: * Collected review tag from Vidya * Fixed the issue reported by Kbot regarding missing declaration 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(-)