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 X-Spam-Level: X-Spam-Status: No, score=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 75B32C2D0BF for ; Tue, 10 Dec 2019 17:55:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5A36A20836 for ; Tue, 10 Dec 2019 17:55:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727527AbfLJRz1 (ORCPT ); Tue, 10 Dec 2019 12:55:27 -0500 Received: from ale.deltatee.com ([207.54.116.67]:38276 "EHLO ale.deltatee.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727259AbfLJRz1 (ORCPT ); Tue, 10 Dec 2019 12:55:27 -0500 Received: from guinness.priv.deltatee.com ([172.16.1.162]) by ale.deltatee.com with esmtp (Exim 4.92) (envelope-from ) id 1iejjI-0006rj-HL; Tue, 10 Dec 2019 10:55:25 -0700 To: Jiasen Lin , linux-kernel@vger.kernel.org, dmaengine@vger.kernel.org, Vinod Koul Cc: Dan Williams , Kit Chow References: <20191210002437.2907-1-logang@deltatee.com> <20191210002437.2907-5-logang@deltatee.com> From: Logan Gunthorpe Message-ID: <23d2c1a3-54fa-db6c-32ee-312a667ac0c9@deltatee.com> Date: Tue, 10 Dec 2019 10:55:22 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-CA Content-Transfer-Encoding: 7bit X-SA-Exim-Connect-IP: 172.16.1.162 X-SA-Exim-Rcpt-To: kchow@gigaio.com, dan.j.williams@intel.com, vkoul@kernel.org, dmaengine@vger.kernel.org, linux-kernel@vger.kernel.org, linjiasen@hygon.cn X-SA-Exim-Mail-From: logang@deltatee.com Subject: Re: [PATCH v2 4/5] dmaengine: plx-dma: Implement hardware initialization and cleanup X-SA-Exim-Version: 4.2.1 (built Wed, 08 May 2019 21:11:16 +0000) X-SA-Exim-Scanned: Yes (on ale.deltatee.com) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2019-12-09 11:49 p.m., Jiasen Lin wrote: > Integrated DMA engine of PEX87xx series switch support various > interrupts. According to my personal experience, I suggest that > enable error interrupt, invalid decscriptor interrupt, abort done > interrupt, graceful puse done interrupt, and > immediate pasue done interrupt by write DMA Channel x Interrupt > Control/Status register. Well, that depends on what we want to do with these interrupts: 1) We shouldn't need to handle the error/invalid descriptor interrupt. We instead just see that a specific descriptor failed (in the usual way) and handle it accordingly. (Though this isn't really documented well). An invalid descriptor should really never happen unless we have a driver bug. I suppose I could print an error message if either occur. 2) We never send an abort or immediate pause to the device, so neither interrupt can ever fire. So there's nothing to do if they do fire and thus no sense enabling them. 3) We do send a graceful pause to the device on teardown but prefer to poll for the end of the pause instead of adding the extra complexity to waiting for an interrupt. So no need for the interrupt. Logan > > Thanks, > Jiasen Lin > >> kref_init(&plxdev->ref); >> INIT_WORK(&plxdev->release_work, plx_dma_release_work); >> + spin_lock_init(&plxdev->ring_lock); >> + tasklet_init(&plxdev->desc_task, plx_dma_desc_task, >> + (unsigned long)plxdev); >> >> + RCU_INIT_POINTER(plxdev->pdev, pdev); >> plxdev->bar = pcim_iomap_table(pdev)[0]; >> >> dma = &plxdev->dma_dev; >> @@ -169,6 +501,16 @@ static void plx_dma_remove(struct pci_dev *pdev) >> >> free_irq(pci_irq_vector(pdev, 0), plxdev); >> >> + rcu_assign_pointer(plxdev->pdev, NULL); >> + synchronize_rcu(); >> + >> + spin_lock_bh(&plxdev->ring_lock); >> + plxdev->ring_active = false; >> + spin_unlock_bh(&plxdev->ring_lock); >> + >> + __plx_dma_stop(plxdev); >> + plx_dma_abort_desc(plxdev); >> + >> plxdev->bar = NULL; >> plx_dma_put(plxdev); >> >>