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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-Disposition: inline In-Reply-To: <676386736df5e5b22e34b0b5af91c894@walle.cc> User-Agent: NeoMutt/20171215 X-EXCLAIMER-MD-CONFIG: e1e8a2fd-e40a-4ac6-ac9b-f7e9cc9ee180 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210312_110716_869500_C2690499 X-CRM114-Status: GOOD ( 12.22 ) X-BeenThere: linux-mtd@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Sender: "linux-mtd" Errors-To: linux-mtd-bounces+linux-mtd=archiver.kernel.org@lists.infradead.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=B0C to +85=B0C. 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. ______________________________________________________ Linux MTD discussion mailing list http://lists.infradead.org/mailman/listinfo/linux-mtd/