Messages in this thread | | | Date | Fri, 12 Mar 2021 16:37:09 +0530 | From | Pratyush Yadav <> | Subject | Re: [RFC PATCH 0/6] spi: Add OSPI PHY calibration support for spi-cadence-quadspi |
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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.
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