ARC: [axs10x] Specify reserved memory for frame buffer
Allocation of a frame buffer memory in a special memory region
allows bypassing of so-called IO Coherency aperture
which is typically set as a range 0x8z-0xAz.
I.e. all data traffic to PGU bypasses IO Coherency block
and saves its bandwidth for other peripherals.
Even though for AXS101 (which sorts ARC770 CPU) IOC is not
an option for a sake of keeping one DT description for the
base-board (axs10x_mb.dtsi) we're still defining reserved
memory location in the very end of DDR.
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Acked-by: Vineet Gupta <vgupta@synopsys.com>
Cc: devicetree@vger.kernel.org
diff --git a/arch/arc/boot/dts/axc003.dtsi b/arch/arc/boot/dts/axc003.dtsi
index f90fadf..35ece04 100644
--- a/arch/arc/boot/dts/axc003.dtsi
+++ b/arch/arc/boot/dts/axc003.dtsi
@@ -100,4 +100,18 @@
device_type = "memory";
reg = <0x80000000 0x20000000>; /* 512MiB */
};
+
+ reserved-memory {
+ #address-cells = <1>;
+ #size-cells = <1>;
+ ranges;
+ /*
+ * Move frame buffer out of IOC aperture (0x8z-0xAz).
+ */
+ frame_buffer: frame_buffer@be000000 {
+ compatible = "shared-dma-pool";
+ reg = <0xbe000000 0x2000000>;
+ no-map;
+ };
+ };
};