Messages in this thread | | | Date | Tue, 28 Mar 2023 11:23:18 +0100 | Subject | Re: [PATCH v3 1/4] ARM: dts: at91-sama5d27_wlsom1: Set sst26vf064b SPI NOR flash at its maximum frequency | From | Tudor Ambarus <> |
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On 3/28/23 11:15, Tudor Ambarus wrote: > From: Tudor Ambarus <tudor.ambarus@microchip.com> >
cut
> Signed-off-by: Tudor Ambarus <tudor.ambarus@linaro.org>
I don't understand why these differ. On my local machine I see them match:
commit e208a7b04cbde950588c561889d2f8eb8a10485f Author: Tudor Ambarus <tudor.ambarus@linaro.org> Date: Thu Nov 17 12:52:46 2022 +0200
ARM: dts: at91-sama5d27_wlsom1: Set sst26vf064b SPI NOR flash at its maximum frequency
sama5d27-wlsom1 populates an sst26vf064b SPI NOR flash. Its maximum operating frequency for 2.7-3.6V is 104 MHz. As the flash is operated at 3.3V, increase its maximum supported frequency to 104MHz. The increasing of the spi-max-frequency value requires the setting of the "CE# Not Active Hold Time", thus set the spi-cs-setup-ns to a value of 7.
The sst26vf064b datasheet specifies just a minimum value for the "CE# Not Active Hold Time" and it advertises it to 5 ns. There's no maximum time specified. I determined experimentally that 5 ns for the spi-cs-setup-ns is not enough when the flash is operated close to its maximum frequency and tests showed that 7 ns is just fine, so set the spi-cs-setup-ns dt property to 7.
With the increase of frequency the reads are now faster with ~37%.
Signed-off-by: Tudor Ambarus <tudor.ambarus@linaro.org>
Anyway, you can keep v2 then, looks like v2 has the same email on both the author line and the S-o-b line. It's fine by me even if it is with @microchip.com: https://lore.kernel.org/all/20230328100723.1593864-2-tudor.ambarus@linaro.org/
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