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Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.11.0 Subject: Re: [Patch v2 2/2] cpufreq: tegra194: use refclk delta based loop instead of udelay Content-Language: en-US To: Jon Hunter , , , , , CC: , , , "Sumit Gupta" References: <20230901164113.29139-1-sumitg@nvidia.com> <20230901164113.29139-3-sumitg@nvidia.com> <8c26f493-76d4-086e-c353-2f60a4ef7a72@nvidia.com> From: Sumit Gupta In-Reply-To: <8c26f493-76d4-086e-c353-2f60a4ef7a72@nvidia.com> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.126.231.35] X-ClientProxiedBy: rnnvmail202.nvidia.com (10.129.68.7) To rnnvmail201.nvidia.com (10.129.68.8) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DS1PEPF0001708E:EE_|IA1PR12MB6282:EE_ X-MS-Office365-Filtering-Correlation-Id: 6070ae3e-4730-4d7d-3b0d-08dbab25203d 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:216.228.117.161;CTRY:US;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:mail.nvidia.com;PTR:dc6edge2.nvidia.com;CAT:NONE;SFS:(13230031)(4636009)(376002)(346002)(39860400002)(136003)(396003)(451199024)(1800799009)(186009)(82310400011)(46966006)(40470700004)(36840700001)(70586007)(70206006)(2906002)(110136005)(4744005)(41300700001)(107886003)(2616005)(31686004)(5660300002)(478600001)(4326008)(16576012)(54906003)(8676002)(8936002)(316002)(6666004)(53546011)(40460700003)(36860700001)(36756003)(47076005)(40480700001)(26005)(16526019)(83380400001)(31696002)(86362001)(7636003)(336012)(426003)(82740400003)(356005)(43740500002);DIR:OUT;SFP:1101; X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 01 Sep 2023 19:53:34.4674 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 6070ae3e-4730-4d7d-3b0d-08dbab25203d X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[216.228.117.161];Helo=[mail.nvidia.com] X-MS-Exchange-CrossTenant-AuthSource: DS1PEPF0001708E.namprd03.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: IA1PR12MB6282 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/09/23 23:29, Jon Hunter wrote: > > On 01/09/2023 17:41, Sumit Gupta wrote: >> Use reference clock count based loop instead of "udelay()" for >> sampling of counters to improve the accuracy of re-generated CPU >> frequency. "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 >> --- > > Same here. > > Jon > This patch is newly added in v2. Thank you, Sumit Gupta