ramips: increase SPI frequency for ASUS RT-AC51U/RT-AC54U
authorAdrian Schmutzler <freifunk@adrianschmutzler.de>
Sun, 17 May 2020 11:50:33 +0000 (13:50 +0200)
committerAdrian Schmutzler <freifunk@adrianschmutzler.de>
Mon, 18 May 2020 09:38:22 +0000 (11:38 +0200)
This increases the SPI frequency for both ASUS RT-AC51U and RT-AC54U.

Speed comparison tests have been performed on RT-AC54U:

- 10Mhz
root@OpenWrt:~# time cat /dev/mtd* > /dev/null
real    4m 37.78s
user    0m 0.02s
sys     2m 43.92s

- 50Mhz
root@OpenWrt:~# time cat /dev/mtd* > /dev/null
real    1m 28.34s
user    0m 0.03s
sys     0m 46.96s

- 50Mhz fast read
root@OpenWrt:~# time cat /dev/mtd* > /dev/null
real    1m 11.94s
user    0m 0.01s
sys     0m 46.94s

- 80Mhz
root@OpenWrt:~# time cat /dev/mtd* > /dev/null
real    1m 12.31s
user    0m 0.04s
sys     0m 46.96s

- 80Mhz fast read
root@OpenWrt:~# time cat /dev/mtd* > /dev/null
real    1m 12.15s
user    0m 0.02s
sys     0m 46.97s

Based on that, we took 50 MHz with fast-read, as higher frequencies
didn't yield further improvements.

For the RT-AC51U, only the final configuration was tested.

Tested-by: Zhijun You <hujy652@gmail.com> [RT-AC54U]
Tested-by: Davide Fioravanti <pantanastyle@gmail.com> [RT-AC51U]
Signed-off-by: Adrian Schmutzler <freifunk@adrianschmutzler.de>
target/linux/ramips/dts/mt7620a_asus_rt-ac5x.dtsi

index 83a789f..3813efa 100644 (file)
@@ -27,7 +27,9 @@
        flash@0 {
                compatible = "jedec,spi-nor";
                reg = <0>;
-               spi-max-frequency = <10000000>;
+
+               spi-max-frequency = <50000000>;
+               m25p,fast-read;
 
                partitions {
                        compatible = "fixed-partitions";