[RFC PATCH 0/1] arm64: dts: ti: k3-j721s2: handling subnode of msmc node

[RFC PATCH 0/1] arm64: dts: ti: k3-j721s2: handling subnode of msmc node

[Udit Kumar]

TI K3 SOCs have msmc sram, part of it can be configured as L3 cache
depending upon system firmware configuration file.

This could be possible to have no L3 cache or variable size of
L3 cache.
In either case top of 64KB of SRAM has to be reserved for system
firmware called tifs.

https://software-dl.ti.com/tisci/esd/latest/2_tisci_msgs/general/core.html?highlight=msmc
Section: TISCI_MSG_QUERY_MSMC.

But u-boot as part of fix up is deleting sysfw and l3cache node
before passing DT to OS
https://github.com/u-boot/u-boot/blob/master/arch/arm/mach-k3/common.c#L412

In my view we can handle in two ways
1) delete tifs node as well
In this case, only accessible sram will be visible to OS
https://lore.kernel.org/all/20230420081128.3617214-1-u-kumar1@ti.com/

2) make these nodes (tifs, atf and l3cache) as reserved,
so that OS has complete view of memory.
This is patch for option 2.

Nishanth suggested to discuss in k.org group
https://lore.kernel.org/all/20230502230022.5pjywy6h7oqrkmwh@elusive/

So sending this patch for suggestion for selection right option.
Also other options are welcome.


Udit Kumar (1):
  arm64: dts: ti: k3-j721s2: Add reserved status in msmc node.

 arch/arm64/boot/dts/ti/k3-j721s2-main.dtsi | 3 +++
 1 file changed, 3 insertions(+)

-- 
2.34.1

[PATCH 1/1] arm64: dts: ti: k3-j721s2: Add reserved status in msmc

[Udit Kumar]

mark atf, l3-cache and tifs node as reserved.

Signed-off-by: Udit Kumar <u-kumar1@ti.com>
---
 arch/arm64/boot/dts/ti/k3-j721s2-main.dtsi | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/arm64/boot/dts/ti/k3-j721s2-main.dtsi b/arch/arm64/boot/dts/ti/k3-j721s2-main.dtsi
index 2dd7865f7654..791993060f44 100644
--- a/arch/arm64/boot/dts/ti/k3-j721s2-main.dtsi
+++ b/arch/arm64/boot/dts/ti/k3-j721s2-main.dtsi
@@ -14,14 +14,17 @@ msmc_ram: sram@70000000 {
 		ranges = <0x0 0x0 0x70000000 0x400000>;
 
 		atf-sram@0 {
+			status = "reserved";
 			reg = <0x0 0x20000>;
 		};
 
 		tifs-sram@1f0000 {
+			status = "reserved";
 			reg = <0x1f0000 0x10000>;
 		};
 
 		l3cache-sram@200000 {
+			status = "reserved";
 			reg = <0x200000 0x200000>;
 		};
 	};
-- 
2.34.1

Re: [PATCH 1/1] arm64: dts: ti: k3-j721s2: Add reserved status in msmc

[Nishanth Menon]

On 20:17-20230503, Udit Kumar wrote:
> Mark atf, l3-cache and tifs node as reserved.

why? (I am not reading the cover-letter for a 1 patch)
> 
> Signed-off-by: Udit Kumar <u-kumar1@ti.com>
> ---
>  arch/arm64/boot/dts/ti/k3-j721s2-main.dtsi | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/arch/arm64/boot/dts/ti/k3-j721s2-main.dtsi b/arch/arm64/boot/dts/ti/k3-j721s2-main.dtsi
> index 2dd7865f7654..791993060f44 100644
> --- a/arch/arm64/boot/dts/ti/k3-j721s2-main.dtsi
> +++ b/arch/arm64/boot/dts/ti/k3-j721s2-main.dtsi
> @@ -14,14 +14,17 @@ msmc_ram: sram@70000000 {
>  		ranges = <0x0 0x0 0x70000000 0x400000>;
>  
>  		atf-sram@0 {
> +			status = "reserved";
>  			reg = <0x0 0x20000>;
>  		};
>  
>  		tifs-sram@1f0000 {
> +			status = "reserved";
>  			reg = <0x1f0000 0x10000>;
>  		};
>  
>  		l3cache-sram@200000 {
> +			status = "reserved";
>  			reg = <0x200000 0x200000>;
>  		};
>  	};
> -- 
> 2.34.1
> 

-- 
Regards,
Nishanth Menon
Key (0xDDB5849D1736249D) / Fingerprint: F8A2 8693 54EB 8232 17A3  1A34 DDB5 849D 1736 249D

Re: [PATCH 1/1] arm64: dts: ti: k3-j721s2: Add reserved status in msmc

[Krzysztof Kozlowski]

On 03/05/2023 16:51, Nishanth Menon wrote:
> On 20:17-20230503, Udit Kumar wrote:
>> Mark atf, l3-cache and tifs node as reserved.
> 
> why? (I am not reading the cover-letter for a 1 patch)

And you should not have to. :) The commit msg should explain why it is
useful.

Best regards,
Krzysztof

Re: [PATCH 1/1] arm64: dts: ti: k3-j721s2: Add reserved status in msmc

[Kumar, Udit]

On 5/3/2023 8:21 PM, Nishanth Menon wrote:
> On 20:17-20230503, Udit Kumar wrote:
>> Mark atf, l3-cache and tifs node as reserved.
> why? (I am not reading the cover-letter for a 1 patch)


My bad , I should have description in patch itself.

Thanks


> [...]
>> 2.34.1
>>