[PATCH 1/4] arm64: dts: ti: k3-j721s2-som-p0: Reserve 1056MiB of global CMA

[Jayesh Choudhary <j-choudhary@ti.com>]

Reserve 1056MiB of global CMA pool which is also marked as re-usable
so that OS can also use this region if peripheral drivers are not
using it.

J721S2 has different multimedia components such as Camera, Dual-
Display and H264 Video Codec which uses CMA for buffer allocations.
Assuming the worst case scenario where all three run in parallel,
below is the calculation:

1) IMX390 camera sensor 1920x1080
-> 1920 width x 1080 height x 2 bytesperpixel x 4 buffers :
   15.820 MiB which is ~16MiB
   J721S2 can support 8 cameras so ~128MiB

2) 3840x2160@30fps MHDP via DisplayPort0
-> 3840 width x 2160 height x 4 bytesperpixel x 2 buffers :
   63.281 MiB which is ~64 MiB

3) 2560x1440@60fps DSI via DisplayPort1
-> 2560 width x 1440 height x 4 bytesperpixel x 2 buffers :
   28.125 MiB which is ~29 MiB

4) H264 Video Codec 1920x1080 resolution:
-> For 1080p resolution codec application, we require ~98-100 MiB
   per channel. We require ~800MiB for 8 channel codec application.

Total comes about 1021MiB. Adding 32MiB for other peripherals and
and additional 3MiB for rounding it off to 1056MiB.

Signed-off-by: Jayesh Choudhary <j-choudhary@ti.com>
---
 arch/arm64/boot/dts/ti/k3-j721s2-som-p0.dtsi | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/arch/arm64/boot/dts/ti/k3-j721s2-som-p0.dtsi b/arch/arm64/boot/dts/ti/k3-j721s2-som-p0.dtsi
index 54fc5c4f8c3f..2d67fc4bd018 100644
--- a/arch/arm64/boot/dts/ti/k3-j721s2-som-p0.dtsi
+++ b/arch/arm64/boot/dts/ti/k3-j721s2-som-p0.dtsi
@@ -25,6 +25,14 @@ reserved_memory: reserved-memory {
 		#size-cells = <2>;
 		ranges;
 
+		/* global cma region */
+		linux,cma {
+			compatible = "shared-dma-pool";
+			reusable;
+			size = <0x00 0x42000000>;
+			linux,cma-default;
+		};
+
 		secure_ddr: optee@9e800000 {
 			reg = <0x00 0x9e800000 0x00 0x01800000>;
 			alignment = <0x1000>;
-- 
2.34.1