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Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.3.2 Subject: Re: [PATCH V1 0/4] GPIO based PCIe Hot-Plug support Content-Language: en-US To: Bjorn Helgaas , lpieralisi@kernel.org, =?UTF-8?Q?Pali_Roh=c3=a1r?= , Jonathan Derrick Cc: Lukas Wunner , bhelgaas@google.com, robh+dt@kernel.org, krzysztof.kozlowski+dt@linaro.org, kw@linux.com, thierry.reding@gmail.com, jonathanh@nvidia.com, mani@kernel.org, Sergey.Semin@baikalelectronics.ru, jszhang@kernel.org, linux-pci@vger.kernel.org, linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, kthota@nvidia.com, mmaddireddy@nvidia.com, sagar.tv@gmail.com, =?UTF-8?Q?Marek_Beh=c3=ban?= References: <2a465222-342a-418b-95af-9948f6ce9065@linux.dev> <20221003180949.GA2104321@bhelgaas> <20221003182147.jp5gn2jpnf4gucdl@pali> From: Vidya Sagar In-Reply-To: <20221003182147.jp5gn2jpnf4gucdl@pali> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-ClientProxiedBy: MA0PR01CA0072.INDPRD01.PROD.OUTLOOK.COM (2603:1096:a01:ad::19) To BN8PR12MB2900.namprd12.prod.outlook.com (2603:10b6:408:69::18) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BN8PR12MB2900:EE_|PH7PR12MB7209:EE_ X-MS-Office365-Filtering-Correlation-Id: 9cacda82-3b1f-4856-9d61-08daa5bd9cfc X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; 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Because it >>>> already implements all required stuff for re-scanning, registering and >>>> unregistering PCIe devices for Root Ports with Slot Capabilities. And I >>>> think that there is no need to have just another (GPIO based) >>>> implementation of PCI hotplug. >>> >>> I did that a few years ago (rejected), but can attest to the robustness of >>> the pcie hotplug code on non-hotplug slots. >>> https://lwn.net/Articles/811988/ >> >> I think the thread is here: >> https://lore.kernel.org/linux-pci/1581120007-5280-1-git-send-email-jonathan.derrick@intel.com/ >> and I'm sorry that my response came across as "rejected". I intended >> it as "this is good ideas and good work and we should keep going". >> >> Bjorn > > Nice! So we have consensus that this is a good idea. Anyway, if you need > help with designing something here, please let me know as I have good > understanding of all (just two) consumers of pci-bridge-emul.c driver. > Thanks all for your comments. I would like to hear from Bjorn / Lorenzo if the design of the current patch series is fine at a high level or I should explore emulating the root port's configuration space to fake slot config/control registers (which in turn depend on the hotplug GPIO interrupt & state to update Presence Detect related bits in Slot status register) and use the PCIe native Hot-plug framework itself to carry out with enabling the Hot-plug functionality? Thanks, Vidya Sagar