Re: [PATCH] arm64: dts: rockchip: remove rk3588 optee node

From: Quentin Schulz <quentin.schulz@cherry.de>
To: Chris Morgan <macromorgan@hotmail.com>
Cc: Chris Morgan <macroalpha82@gmail.com>,
	linux-rockchip@lists.infradead.org, devicetree@vger.kernel.org,
	sebastian.reichel@collabora.com, heiko@sntech.de,
	conor+dt@kernel.org, krzk+dt@kernel.org, robh@kernel.org
Subject: Re: [PATCH] arm64: dts: rockchip: remove rk3588 optee node
Date: Mon, 3 Feb 2025 17:32:53 +0100	[thread overview]
Message-ID: <7266daa9-b031-4c45-8711-c4e6e4be7095@cherry.de> (raw)
In-Reply-To: <DM6PR19MB3722A5CCBF3FBEAC59189642A5E82@DM6PR19MB3722.namprd19.prod.outlook.com>

Hi Chris,

On 1/31/25 5:59 PM, Chris Morgan wrote:
> On Fri, Jan 31, 2025 at 05:46:20PM +0100, Quentin Schulz wrote:
>> Hi Chris,
>>
>> On 1/30/25 7:10 PM, Chris Morgan wrote:
[...]
>>> When Optee is not present or used, the node will trigger a probe
>>> that generates a (harmless) message on the kernel log.
>>>
>>
>> And what if we have OP-TEE without this node present, which would be
>> possible if we have CONFIG_SPL_ATF_NO_PLATFORM_PARAM set in U-Boot?
>>
>> I guess we could detect from U-Boot if a TEE is loaded as part of u-boot.itb
>> and fixup the DTB otherwise to mark this node as status = "disabled"?
>>
> 
> Based on my understanding of how each of these projects communicate
> with each other, Optee can only work if you either include both the
> Optee node in the firmware AND the reserved memory nodes yourself, or
> if you have neither and let U-Boot do it (by including each of these
> patches as well as setting the CONFIG_SPL_ATF_NO_PLATFORM_PARAM). So
> basically just this node alone is insufficient for it to work today.
> 

Therefore I think we should either have this node defined + the 
reserved-memory node (with hardcoded address and size if guaranteed to 
be stable forever) added or nothing.

Can we mark a reserved-memory node as "disabled"? If not, then we should 
rather have nothing at all I believe.

> The core issue is that Optee requires you to map the memory as
> reserved so that Linux doesn't try to use it. You can either do that
> yourself or you can have U-Boot do it automatically. Having the Optee
> node in the devicetree makes no sense today unless we also carve out
> the memory.
> 

We should patch U-boot to add these nodes to the DT if an OP-TEE OS is 
passed and either SPL_ATF_NO_PLATFORM_PARAM=y or we cannot detect the 
OP-TEE nodes in the kernel DT. What do you think?

Cheers,
Quentin

_______________________________________________
Linux-rockchip mailing list
Linux-rockchip@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-rockchip