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=-7.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 55D9BC433E9 for ; Fri, 12 Mar 2021 11:08:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 39B5F64FEE for ; Fri, 12 Mar 2021 11:08:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233373AbhCLLHq (ORCPT ); Fri, 12 Mar 2021 06:07:46 -0500 Received: from fllv0016.ext.ti.com ([198.47.19.142]:60036 "EHLO fllv0016.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233641AbhCLLHW (ORCPT ); Fri, 12 Mar 2021 06:07:22 -0500 Received: from fllv0035.itg.ti.com ([10.64.41.0]) by fllv0016.ext.ti.com (8.15.2/8.15.2) with ESMTP id 12CB7BTr067919; Fri, 12 Mar 2021 05:07:11 -0600 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ti.com; s=ti-com-17Q1; t=1615547231; bh=ppnSwE3fKaBg0neIztuqXvH2QrPjE/AfI+3qNHSV6wo=; h=Date:From:To:CC:Subject:References:In-Reply-To; b=REHTjEo5aenRX8Q/huU1uf1giLvZ2+sOJw6Sjd86J71wAnWEOLQjIIQ1hugv6hUTH A6vfQFIbG/Qf0QDysyt9s9uFku4WCBXc5gghZ0NdFjmKyuMfKhAAK1LvRyFo63fV9H 8CE3A9RPz45iOuBmEJ8o0lK6flj9ZwI/qilojN7E= Received: from DFLE111.ent.ti.com (dfle111.ent.ti.com [10.64.6.32]) by fllv0035.itg.ti.com (8.15.2/8.15.2) with ESMTPS id 12CB7BKD116117 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=FAIL); Fri, 12 Mar 2021 05:07:11 -0600 Received: from DFLE114.ent.ti.com (10.64.6.35) by DFLE111.ent.ti.com (10.64.6.32) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2176.2; Fri, 12 Mar 2021 05:07:10 -0600 Received: from fllv0039.itg.ti.com (10.64.41.19) by DFLE114.ent.ti.com (10.64.6.35) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2176.2 via Frontend Transport; Fri, 12 Mar 2021 05:07:10 -0600 Received: from localhost (ileax41-snat.itg.ti.com [10.172.224.153]) by fllv0039.itg.ti.com (8.15.2/8.15.2) with ESMTP id 12CB7Apw023321; Fri, 12 Mar 2021 05:07:10 -0600 Date: Fri, 12 Mar 2021 16:37:09 +0530 From: Pratyush Yadav To: Michael Walle CC: , , , , , , , , , , , , , Subject: Re: [RFC PATCH 0/6] spi: Add OSPI PHY calibration support for spi-cadence-quadspi Message-ID: <20210312110707.lrabch4ketqyyepn@ti.com> References: <20210311191216.7363-1-p.yadav@ti.com> <9c551f56-4c00-b41a-f051-8b7e197fbcdc@microchip.com> <20210312101036.jfz2733ssv4nhfey@ti.com> <676386736df5e5b22e34b0b5af91c894@walle.cc> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <676386736df5e5b22e34b0b5af91c894@walle.cc> User-Agent: NeoMutt/20171215 X-EXCLAIMER-MD-CONFIG: e1e8a2fd-e40a-4ac6-ac9b-f7e9cc9ee180 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/03/21 11:20AM, Michael Walle wrote: > Am 2021-03-12 11:10, schrieb Pratyush Yadav: > > There is usually a delay from when the flash drives the data line (IOW, > > puts a data bit on it) and when the signal reaches the controller. This > > delay can vary by the flash, board, silicon characteristics, > > temperature, etc. > > Temperature might change over time, but the calibration is only done > once. I don't know how much influence the temperature actually has, but > our boards are usually operating from -40°C to +85°C. So there might be > a possible temperature difference of 125K between actual calibration and > when the flash is accessed. The algorithm supports a temperature range of -45 C to +130 C. The temperature is checked at calibration time and adjustments are made to make sure the reads work over the entire temperature range [0]. [0] The current implementation does not have a way to query the temperature from the sensor (see cqspi_get_temp()), so it always assumes the temperature at calibration time is 45 C. But that can be added later once the temperature sensor driver is implemented. -- Regards, Pratyush Yadav Texas Instruments Inc.