linux-kernel - Re: [PATCH v3 8/9] mailbox: mediatek: Add CMDQ secure mailbox driver

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Date: Tue, 26 Dec 2023 07:57:40 +0000
From: CK Hu (胡俊光) <ck.hu@...iatek.com>
To: "jassisinghbrar@...il.com" <jassisinghbrar@...il.com>,
	"matthias.bgg@...il.com" <matthias.bgg@...il.com>,
	Jason-JH Lin (林睿祥) <Jason-JH.Lin@...iatek.com>,
	"angelogioacchino.delregno@...labora.com"
	<angelogioacchino.delregno@...labora.com>, "robh+dt@...nel.org"
	<robh+dt@...nel.org>, "krzysztof.kozlowski+dt@...aro.org"
	<krzysztof.kozlowski+dt@...aro.org>, "chunkuang.hu@...nel.org"
	<chunkuang.hu@...nel.org>
CC: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-mediatek@...ts.infradead.org" <linux-mediatek@...ts.infradead.org>,
	Singo Chang (張興國) <Singo.Chang@...iatek.com>,
	Johnson Wang (王聖鑫) <Johnson.Wang@...iatek.com>,
	"linux-media@...r.kernel.org" <linux-media@...r.kernel.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	Jason-ch Chen (陳建豪)
	<Jason-ch.Chen@...iatek.com>, Shawn Sung (宋孝謙)
	<Shawn.Sung@...iatek.com>, "mchehab@...nel.org" <mchehab@...nel.org>,
	Nancy Lin (林欣螢) <Nancy.Lin@...iatek.com>,
	"conor+dt@...nel.org" <conor+dt@...nel.org>,
	Project_Global_Chrome_Upstream_Group
	<Project_Global_Chrome_Upstream_Group@...iatek.com>,
	"linux-arm-kernel@...ts.infradead.org" <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v3 8/9] mailbox: mediatek: Add CMDQ secure mailbox driver

Hi, Jason:

On Fri, 2023-12-22 at 12:52 +0800, Jason-JH.Lin wrote:
> To support secure video path feature, GCE have to read/write
> registgers
> in the secure world. GCE will enable the secure access permission to
> the
> HW who wants to access the secure content buffer.
> 
> Add CMDQ secure mailbox driver to make CMDQ client user is able to
> sending their HW settings to the secure world. So that GCE can
> execute
> all instructions to configure HW in the secure world.
> 
> Signed-off-by: Jason-JH.Lin <jason-jh.lin@...iatek.com>
> ---

[snip]

> +
> +static u32 cmdq_sec_get_cookie(struct cmdq_sec *cmdq, u32 idx)
> +{
> +	return *(u32 *)(cmdq->shared_mem->va +
> +		CMDQ_SEC_SHARED_THR_CNT_OFFSET + idx * sizeof(u32));
> +}

cmdq_sec_get_cookie() is called in normal context not irq context, so
we could allow a function call into TEE to query cookie even though the
function call would take time. Therefore, it's not necessary to use a
cmdq command to copy cookie value into share memory.

Regards,
CK