| Message ID | 20230328101517.1595738-4-tudor.ambarus@linaro.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | ARM: dts: at91: Set sst26vf064b SPI NOR flash at its maxumum frequency | expand |
On 28/03/2023 at 12:15, Tudor Ambarus wrote: > From: Tudor Ambarus <tudor.ambarus@microchip.com> > > sama5d2_icp 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> Tested-by: Nicolas Ferre <nicolas.ferre@microchip.com> # on sama5d2 ICP board with a linux-next kernel today. Thanks Tudor! Best regards, Nicolas > --- > arch/arm/boot/dts/at91-sama5d2_icp.dts | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/arch/arm/boot/dts/at91-sama5d2_icp.dts b/arch/arm/boot/dts/at91-sama5d2_icp.dts > index 1346b8f2b259..999adeca6f33 100644 > --- a/arch/arm/boot/dts/at91-sama5d2_icp.dts > +++ b/arch/arm/boot/dts/at91-sama5d2_icp.dts > @@ -669,7 +669,8 @@ flash@0 { > #size-cells = <1>; > compatible = "jedec,spi-nor"; > reg = <0>; > - spi-max-frequency = <80000000>; > + spi-max-frequency = <104000000>; > + spi-cs-setup-ns = <7>; > spi-tx-bus-width = <4>; > spi-rx-bus-width = <4>; > m25p,fast-read; > -- > 2.40.0.348.gf938b09366-goog >
diff --git a/arch/arm/boot/dts/at91-sama5d2_icp.dts b/arch/arm/boot/dts/at91-sama5d2_icp.dts index 1346b8f2b259..999adeca6f33 100644 --- a/arch/arm/boot/dts/at91-sama5d2_icp.dts +++ b/arch/arm/boot/dts/at91-sama5d2_icp.dts @@ -669,7 +669,8 @@ flash@0 { #size-cells = <1>; compatible = "jedec,spi-nor"; reg = <0>; - spi-max-frequency = <80000000>; + spi-max-frequency = <104000000>; + spi-cs-setup-ns = <7>; spi-tx-bus-width = <4>; spi-rx-bus-width = <4>; m25p,fast-read;