[PATCH 0/2] Do not reserve memory for coprocessor FW

[PATCH 0/2] Do not reserve memory for coprocessor FW

[Andrei Lalaev]

Milk-V Duo and Duo-256M reserve a region for coprocessor FW at
the end of RAM. It is not correct because:
  - FSBL can be configured to load FW into a different region
  - if no firmware is loaded, the reserved memory is wasted

As explained in [1, 2], FSBL should reserve the region at runtime.

The latest FSBL can boot the system without coprocessor FW:
  FSBL Jb2829:g6f8962c394dd-dirty:2026-09-20T13:04:17+00:00
  st_on_reason=d0000
  st_off_reason=0
  P2S/0x1000/0xc00fa00.
  SD/0xaa00/0x1000/0x1000/0.P2E.
  cv181x DDR init.
  ddr_param[0]=0x0.
  pkg_type=5
  D1_3_2
  DDR3-2G-QFN
  Data rate=1866.
  DDR BIST PASS
  PLLS.
  PLLE.
  C2S/0x0/0x0/0x0.
  No C906L image.
  MS/0xba00/0x80000000/0x43e00.
  SD/0xba00/0x43e00/0x43e00/0.ME.
  L2/0x4f800.
  SD/0x4f800/0x200/0x200/0.L2/0x33334c42/0xcafe4b49/0x80200000/0x8c200/0x8c200
  SD/0x4f800/0x8c200/0x8c200/0.sys_switch_all_to_pll...
  Loader_2nd loaded.
  Use internal 32k

So it is safe to remove `coprocessor_rtos` nodes.

[1]: https://lore.kernel.org/sophgo/6e4b5c98-7d48-4629-a6a0-4d930327f9a0@sifive.com/
[2]: https://lore.kernel.org/sophgo/aqrhRic7Ww6fPhxg@pie/

Signed-off-by: Andrei Lalaev <andrey.lalaev@gmail.com>
---
Andrei Lalaev (2):
      riscv: dts: sophgo: cv1800b-milkv-duo: drop reserved memory node
      riscv: dts: sophgo: sg2002-milkv-duo256m: drop reserved memory node

 arch/riscv/boot/dts/sophgo/cv1800b-milkv-duo.dts    | 11 -----------
 arch/riscv/boot/dts/sophgo/sg2002-milkv-duo256m.dts | 11 -----------
 2 files changed, 22 deletions(-)
---
base-commit: 93f51579e7df248780214094418f205253383cc5
change-id: 20260921-sophgo-remove-coprocessor-node-4e6c59ab58d2

Best regards,
--  
Andrei Lalaev <andrey.lalaev@gmail.com>

[PATCH 1/2] riscv: dts: sophgo: cv1800b-milkv-duo: drop reserved memory node

[Andrei Lalaev]

The current FSBL can load firmware to any address and can also
disable the coprocessor. Therefore, FSBL should modify the device
tree at runtime. Remove the node accordingly.

Signed-off-by: Andrei Lalaev <andrey.lalaev@gmail.com>
---
 arch/riscv/boot/dts/sophgo/cv1800b-milkv-duo.dts | 11 -----------
 1 file changed, 11 deletions(-)

diff --git a/arch/riscv/boot/dts/sophgo/cv1800b-milkv-duo.dts b/arch/riscv/boot/dts/sophgo/cv1800b-milkv-duo.dts
index 0e6d79e6e3a4..02848bae2e16 100644
--- a/arch/riscv/boot/dts/sophgo/cv1800b-milkv-duo.dts
+++ b/arch/riscv/boot/dts/sophgo/cv1800b-milkv-duo.dts
@@ -22,17 +22,6 @@ aliases {
 	chosen {
 		stdout-path = "serial0:115200n8";
 	};
-
-	reserved-memory {
-		#address-cells = <1>;
-		#size-cells = <1>;
-		ranges;
-
-		coprocessor_rtos: region@83f40000 {
-			reg = <0x83f40000 0xc0000>;
-			no-map;
-		};
-	};
 };
 
 &osc {

-- 
2.55.0

[PATCH 2/2] riscv: dts: sophgo: sg2002-milkv-duo256m: drop reserved memory node

[Andrei Lalaev]

The current FSBL can load firmware to any address and can also
disable the coprocessor. Therefore, FSBL should modify the device
tree at runtime. Remove the node accordingly.

Signed-off-by: Andrei Lalaev <andrey.lalaev@gmail.com>
---
 arch/riscv/boot/dts/sophgo/sg2002-milkv-duo256m.dts | 11 -----------
 1 file changed, 11 deletions(-)

diff --git a/arch/riscv/boot/dts/sophgo/sg2002-milkv-duo256m.dts b/arch/riscv/boot/dts/sophgo/sg2002-milkv-duo256m.dts
index a2797c0bd767..d4e86c15664e 100644
--- a/arch/riscv/boot/dts/sophgo/sg2002-milkv-duo256m.dts
+++ b/arch/riscv/boot/dts/sophgo/sg2002-milkv-duo256m.dts
@@ -36,17 +36,6 @@ led-0 {
 			linux,default-trigger = "heartbeat";
 		};
 	};
-
-	reserved-memory {
-		#address-cells = <1>;
-		#size-cells = <1>;
-		ranges;
-
-		coprocessor_rtos: region@8fe00000 {
-			reg = <0x8fe00000 0x200000>;
-			no-map;
-		};
-	};
 };
 
 &osc {

-- 
2.55.0