Re: [PATCH v3 3/4] ARM: dts: at91: sama5d2_icp: Set sst26vf064b SPI NOR flash at its maximum frequency

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On 28/03/2023 at 12:15, Tudor Ambarus wrote:
From: Tudor Ambarus <tudor.ambarus@xxxxxxxxxxxxx>

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@xxxxxxxxxx>

Tested-by: Nicolas Ferre <nicolas.ferre@xxxxxxxxxxxxx> # 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


--
Nicolas Ferre




[Index of Archives]     [Device Tree Compilter]     [Device Tree Spec]     [Linux Driver Backports]     [Video for Linux]     [Linux USB Devel]     [Linux PCI Devel]     [Linux Audio Users]     [Linux Kernel]     [Linux SCSI]     [XFree86]     [Yosemite Backpacking]


  Powered by Linux