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 93452EB64DD for ; Thu, 27 Jul 2023 03:45:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231549AbjG0Dpt (ORCPT ); Wed, 26 Jul 2023 23:45:49 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46312 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231526AbjG0Dpi (ORCPT ); Wed, 26 Jul 2023 23:45:38 -0400 Received: from out30-97.freemail.mail.aliyun.com (out30-97.freemail.mail.aliyun.com [115.124.30.97]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 69F1F2736; Wed, 26 Jul 2023 20:45:29 -0700 (PDT) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R141e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018046051;MF=xueshuai@linux.alibaba.com;NM=1;PH=DS;RN=14;SR=0;TI=SMTPD_---0VoJ3IwC_1690429524; Received: from 30.240.115.26(mailfrom:xueshuai@linux.alibaba.com fp:SMTPD_---0VoJ3IwC_1690429524) by smtp.aliyun-inc.com; Thu, 27 Jul 2023 11:45:25 +0800 Message-ID: <634f4762-cf2e-4535-f369-4032d65093f0@linux.alibaba.com> Date: Thu, 27 Jul 2023 11:45:22 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0) Gecko/20100101 Thunderbird/102.12.0 Subject: Re: [PATCH v6 0/4] drivers/perf: add Synopsys DesignWare PCIe PMU driver support Content-Language: en-US To: Bjorn Helgaas , Jonathan Cameron , Will Deacon Cc: chengyou@linux.alibaba.com, kaishen@linux.alibaba.com, yangyicong@huawei.com, will@kernel.org, baolin.wang@linux.alibaba.com, robin.murphy@arm.com, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-pci@vger.kernel.org, rdunlap@infradead.org, mark.rutland@arm.com, zhuo.song@linux.alibaba.com References: <20230725205955.GA665326@bhelgaas> From: Shuai Xue In-Reply-To: <20230725205955.GA665326@bhelgaas> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2023/7/26 04:59, Bjorn Helgaas wrote: > On Mon, Jul 24, 2023 at 10:18:07AM +0100, Jonathan Cameron wrote: >> On Mon, 24 Jul 2023 10:34:08 +0800 >> Shuai Xue wrote: >>> On 2023/7/10 20:04, Shuai Xue wrote: >>>> On 2023/6/16 16:39, Shuai Xue wrote: >>>>> On 2023/6/6 15:49, Shuai Xue wrote: > >>>>>> This patchset adds the PCIe Performance Monitoring Unit (PMU) driver support >>>>>> for T-Head Yitian 710 SoC chip. Yitian 710 is based on the Synopsys PCI Express >>>>>> Core controller IP which provides statistics feature. > >> ... >> Really a question for Bjorn I think, but here is my 2 cents... >> >> The problem here is that we need to do that fundamental redesign of the >> way the PCI ports drivers work. I'm not sure there is a path to merging >> this until that is done. The bigger problem is that I'm not sure anyone >> is actively looking at that yet. I'd like to look at this (as I have >> the same problem for some other drivers), but it is behind various >> other things on my todo list. >> >> Bjorn might be persuaded on a temporary solution, but that would come >> with some maintenance problems, particularly when we try to do it >> 'right' in the future. Maybe adding another service driver would be >> a stop gap as long as we know we won't keep doing so for ever. Not sure. > > I think the question here is around the for_each_pci_dev() in > __dwc_pcie_pmu_probe()? I don't *like* that because of the > assumptions it breaks (autoload doesn't work, hotplug doesn't work), > but: > > - There are several other drivers that also do this, > - I don't have a better suggest for any of them, > - It's not a drivers/pci thing, so not really up to me anyway, > > so I don't have any problem with this being merged as-is, as long as > you can live with the limitations. > > I don't think this series does anything to work around those > limitations, i.e., it doesn't make up fake device IDs for module > loading or fake events for hotplug, so it seems like we could improve > the implementation later if we ever have a way to do it. > > Bjorn + Will Ok, thank you for confirmation, Bjorn. Then it comes to perf driver parts and it is really a question for @Will I think. What's your opinion about merging this patch set, @Will? Best Regards, Shuai