ARM: dts: am437xx: Enable NAND dma prefetch by default

Currently the default method of prefetch polled shows the highest
possible read and write speed when minimal non NAND background
activity is being done. But it is also very CPU intensive to reach
these high speeds (CPU load of 99% via mtd performance tests). While
DMA prefetch only uses 50% of the CPU to achieve around 23% less in
top read and write performance.

However, as the non NAND CPU load increases the read and write
performance takes a large hit when using polled prefetch. Therefore,
prefetch dma mode ends up outperforming prefetch polled in general
"system level" test. So switch to using dma prefetch by default since
it is likely what most users would prefer.

Signed-off-by: Franklin S Cooper Jr <fcooper@ti.com>
Acked-by: Roger Quadros <rogerq@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>

diff --git a/arch/arm/boot/dts/am437x-gp-evm.dts b/arch/arm/boot/dts/am437x-gp-evm.dts
index ee76021c7f3434556dc0ce577a19cbeda91c0577..afb8eb0a0a16ee63ea1ece64e694ac847c249067 100644 (file)
--- a/arch/arm/boot/dts/am437x-gp-evm.dts
+++ b/arch/arm/boot/dts/am437x-gp-evm.dts
@@ -856,6 +856,7 @@
                interrupts = <0 IRQ_TYPE_NONE>, /* fifoevent */
                             <1 IRQ_TYPE_NONE>; /* termcount */
                rb-gpios = <&gpmc 0 GPIO_ACTIVE_HIGH>;  /* gpmc_wait0 */
+               ti,nand-xfer-type = "prefetch-dma";
                ti,nand-ecc-opt = "bch16";
                ti,elm-id = <&elm>;
                nand-bus-width = <8>;

diff --git a/arch/arm/boot/dts/am43x-epos-evm.dts b/arch/arm/boot/dts/am43x-epos-evm.dts
index 54f40f370011c211664a6583a845146b50b996af..9d276af7c539f3dd1cb382f12d4bca7d9bd2fb3d 100644 (file)
--- a/arch/arm/boot/dts/am43x-epos-evm.dts
+++ b/arch/arm/boot/dts/am43x-epos-evm.dts
@@ -564,6 +564,7 @@
                interrupts = <0 IRQ_TYPE_NONE>, /* fifoevent */
                             <1 IRQ_TYPE_NONE>; /* termcount */
                rb-gpios = <&gpmc 0 GPIO_ACTIVE_HIGH>;  /* gpmc_wait0 */
+               ti,nand-xfer-type = "prefetch-dma";
                ti,nand-ecc-opt = "bch16";
                ti,elm-id = <&elm>;
                nand-bus-width = <8>;