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Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.13.0 Subject: Re: [Patch] driver: cpufreq: use refclk delta based loop instead of udelay Content-Language: en-US To: Sumit Gupta , rafael@kernel.org, viresh.kumar@linaro.org, linux-pm@vger.kernel.org, linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org Cc: treding@nvidia.com, bbasu@nvidia.com References: <20230901152046.25662-1-sumitg@nvidia.com> From: Jon Hunter In-Reply-To: <20230901152046.25662-1-sumitg@nvidia.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-ClientProxiedBy: LO4P123CA0639.GBRP123.PROD.OUTLOOK.COM (2603:10a6:600:296::6) To CO6PR12MB5444.namprd12.prod.outlook.com (2603:10b6:5:35e::8) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: CO6PR12MB5444:EE_|DS7PR12MB5815:EE_ X-MS-Office365-Filtering-Correlation-Id: 9ef86c18-452d-4944-48ef-08dbab044b72 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:CO6PR12MB5444.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230031)(39860400002)(396003)(376002)(346002)(366004)(136003)(451199024)(1800799009)(186009)(4744005)(2906002)(6666004)(5660300002)(86362001)(55236004)(53546011)(316002)(478600001)(6506007)(2616005)(107886003)(6486002)(4326008)(8676002)(31686004)(31696002)(6512007)(8936002)(26005)(38100700002)(41300700001)(36756003)(83380400001)(66946007)(66476007)(66556008)(45980500001)(43740500002);DIR:OUT;SFP:1101; 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"udelay()" internally calls "WFE" which stops the > counters and results in bigger delta between the last set freq > and the re-generated value from counters. The counter sampling > window used in loop is the minimum number of reference clock > cycles which is known to give a stable value of CPU frequency. > The change also helps to reduce the sampling window from "500us" > to "<50us". > > Suggested-by: Antti Miettinen > Signed-off-by: Sumit Gupta Please can you correct the subject and drop the 'driver:'. Jon -- nvpublic